MICRF505LYML TR - Micrel - Datasheet.Directory

MICRF505L

850MHz and 950MHz ISM Band

Transceiver

MLF and MicroLead Frame is a registered trademark of Amkor Technologies

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

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General Description

The MICRF505 is a true single-chip, frequency shift

keying (FSK) transceiver intended for use in half-

duplex, bidirectional RF links. The multi-channeled

FSK transceiver is intended for UHF radio

equipment in compliance with the with the North

American Federal Communications Commission

(FCC) part 15.247 and the European

Telecommunication Standard Institute (ETSI)

specification, EN300 220.

The transmitter consists of a PLL frequency

synthesizer and power amplifier. The frequency

synthesizer consists of a voltage-controlled oscillator

(VCO), a crystal oscillator, dual modulus prescaler,

programmable frequency dividers, and a phase-

detector. The loop-filter is external for flexibility and

can be a simple passive circuit. The output power of

the power amplifier can be programmed to seven

levels. A lock-detect circuit detects when the PLL is

in lock. In receive mode, the PLL synthesizer

generates the local oscillator (LO) signal. The N, M,

and A values that give the LO frequency are stored

in the N0, M0, and A0 registers.

The receiver is a zero intermediate frequency (IF)

type which makes channel filtering possible with low-

power, integrated low-pass filters. The receiver

consists of a low noise amplifier (LNA) that drives a

quadrature mix pair. The mixer outputs feed two

identical signal channels in phase quadrature. Each

channel includes a pre-amplifier, a third order

Sallen-Key RC low-pass filter that protects the

following switched-capacitor filter from strong

adjacent channel signals, and a limiter. The main

channel filter is a switched-capacitor implementation

of a six-pole elliptic low pass filter. The cut-off

frequency of the Sallen-Key RC filter can be

programmed to four different frequencies: 100kHz,

150kHz, 230kHz, and 340kHz. The I and Q channel

outputs are demodulated and produce a digital data

output. The demodulator detects the relative phase

of the I and the Q channel signal. If the I channel

signal lags behind the Q channel, the FSK tone

frequency is above the LO frequency (data '1'). If the

I channel leads the Q channel, the FSK tone is

below the LO frequency (data '0'). The output of the

receiver is available on the DataIXO pin. A receive

signal strength indicator (RSSI) circuit indicates the

received signal level. All support documentation can

be found on Micrel’s web site at www.micrel.com.

RadioWire®

Features

• True single chip transceiver

• Digital bit synchronizer

• Received signal strength indicator (RSSI)

• RX and TX power management

• Power down function

• Reference crystal tuning capabilities

• Frequency error estimator

• Baseband shaping

• Three-wire programmable serial interface

• Register read back function

Applications

• Telemetry

• Remote metering

• Wireless controller

• Remote data repeater

• Remote control systems

• Wireless modem

• Wireless security system

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General Description ............................................................................................................................................... 1

Features ................................................................................................................................................................. 1

Applications ............................................................................................................................................................ 1

RadioWire® RF Selection Guide ........................................................................................................................... 4

Ordering Information .............................................................................................................................................. 4

Block Diagram........................................................................................................................................................ 4

Pin Configuration.................................................................................................................................................... 5

Pin Description ....................................................................................................................................................... 5

Absolute Maximum Ratings(1) ................................................................................................................................6

Operating Ratings(2) ............................................................................................................................................... 6

Electrical Characteristics(4) ..................................................................................................................................... 6

Programming.......................................................................................................................................................... 9

Writing to the control registers in MICRF505 ....................................................................................................... 10

Writing to a Single Register ................................................................................................................................. 10

Writing to All Registers......................................................................................................................................... 11

Writing to n Registers having Incremental Addresses ......................................................................................... 11

Writing to n Registers having Non-Incremental Addresses ................................................................................. 12

Reading from the control registers in MICRF505 ................................................................................................ 12

Programming interface timing .............................................................................................................................. 12

Power on Reset.................................................................................................................................................... 13

Programming summary........................................................................................................................................ 14

Frequency Synthesizer ........................................................................................................................................ 15

Crystal Oscillator (XCO).................................................................................................................................... 16

VCO...................................................................................................................................................................... 17

Charge Pump...................................................................................................................................................... 18

PLL Filter............................................................................................................................................................. 18

Lock Detect......................................................................................................................................................... 18

Modes of Operation ........................................................................................................................................... 18

Low Dropout Regulator ........................................................................................................................................ 19

Transceiver Sync/Non-Synchronous Mode ......................................................................................................... 20

Data Interface....................................................................................................................................................... 20

Receiver ............................................................................................................................................................... 21

Front End ............................................................................................................................................................ 21

Sallen-Key Filters............................................................................................................................................... 21

Switched Capacitor Filter.................................................................................................................................. 22

RSSI..................................................................................................................................................................... 22

FEE ...................................................................................................................................................................... 23

Bit Synchronizer................................................................................................................................................. 24

Transmitter ........................................................................................................................................................... 25

Power Amplifier.................................................................................................................................................. 25

Modulator............................................................................................................................................................ 27

Using the XCO-tune Bits ...................................................................................................................................... 29

Typical Application ............................................................................................................................................... 31

MICRF505LBML/YML Land pattern..................................................................................................................... 32

Layout Considerations ......................................................................................................................................... 33

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Package Information MICRF505LBML ................................................................................................................ 34

Package Information MICRF505YML .................................................................................................................. 35

Overview of programming bit ............................................................................................................................... 36

Table 1: Detailed description of programming bit ................................................................................................ 36

Table 2: Main Mode bit......................................................................................................................................... 41

Table 3: Synchronizer mode bit ........................................................................................................................... 41

Table 4: Modulation bit......................................................................................................................................... 41

Table 5: Prefilter bit .............................................................................................................................................. 41

Table 6: Power amplifier bit ................................................................................................................................. 42

Table 7:Generation of Bitrate_clk, BitSync_clk and Mod_clk. ............................................................................. 42

Table 8: Test signals ............................................................................................................................................ 42

Table 10: Frequency Error Estimation control bit ................................................................................................ 43

Table 11: Frequency Error Estimation control bit, cont........................................................................................ 43

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RadioWire® RF Selection Guide

Device Frequency Range

Maximum

Data Rate Receive Supply

Voltage Transmit

Modulation

Type Package

MICRF500 700MHz – 1.1GHz 128k Baud 12mA 2.5 to 3.4V 50mA FSK LQFP-44

MICRF501 300MHz – 440MHz 128k Baud 8mA 2.5 to 3.4V 45mA FSK LQFP-44

MICRF505 850MHz – 950MHz 200k Baud 13mA 2.0 to 2.5V 28mA FSK MLF™-32

MICRF506 410MHz – 450MHz 200k Baud 12mA 2.0 to 2.5V 21.5mA FSK MLF™-32

MICRF405 290-980MHz 200k Baud NA 2.0-3.6V 18mA FSK/ASK MLF™-24

Ordering Information

Part Number Junction Temp. Range(1) Package

MICRF505LYML TR –40° to +85°C Lead free 32-Pin MLFTM

____________________________________________________________________________________________________

Block Diagram

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Pin Configuration

MICRF505LBML

MLF32

LDOen

PTATBIAS

RFVDD

RFGND

ANT

RFGND

VDDIN

PABIAS

CIBIAS

IFVDD

IFGND

ICHOUT

QCHOUT

RSSI

VDDOUT

DATACLK

DATAIXO

SCLK

XTALIn

XTALOUT

LDOByp

DIGVDD

DIGGND

CPOUT

GND

VARIN

VCOGND

VCOVDD

MICRF505LYML

32-Pin MLFTM

Pin Description

Number Pin Name Type Pin Function

1 LDOen I LDO enable, High

2 PTATBIAS O

Connection for bias

resistor.

3 RFVDD

LNA and PA power

supply.

4 RFGND LNA and PA ground.

5 ANT I/O Antenna In/Output.

6 RFGND LNA and PA ground.

7 PAbias PA Bias /ASK DATAin

8 VDDin

LDO VDDin, Max

VDD=6V

9 CIBIAS O

Connection for bias

resistor.

10 IFVDD IF/mixer power supply.

11 IFGND IF/mixer ground.

12 ICHOUT O Test pin.

13 QCHOUT O Test pin.

14 RSSI O

Received signal strength

indicator.

15 LD O PLL lock detect.

16 VDDOUT LDO output

17 DATACLK O Rx/Tx data clock out

Number Pin Name Type Pin Function

18 DATAIXO I/O RX/TX data input out put

19 IO I/O

3-wire interface data

in/output.

20 SCLK I

3-wire interface serial

clock.

21 CS I

3-wire interface chip

select.

22 XTALIN I Crystal oscillator input.

23 XTALOUT O Crystal oscillator output.

24 LDOByp LDO reference bypass

25 DIGVDD Digital power supply.

26 DIGGND Digital ground.

27 CPOUT O PLL charge pump output.

28 GND Substrate ground.

29 VARIN I VCO varactor.

30 VCOGND VCO ground.

31 VCOVDD VCO power supply.

32 NC No connect,VCO Bias

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Absolute Maximum Ratings(1)

Supply Voltage (VDD).........................................+2.7V

Voltage on any pin (GND = 0V). ..... -0.3V to 2.7V

Supply Voltage VDDin…………………………..0 to 6V

Storage Temperature (Ts) ................ -55°C to +150°C

ESD Rating(3)........................................................ 2kV

Operating Ratings(2)

Supply voltage (VDDIn)………..…….+2.25V to +5.5V

RF Frequencies.......................... 850MHz to 950MHz

Data Rate ................................................<200kBaud

Ambient Temperature (TA) ................ –40°C to +85°C

Package Thermal Resistance

MLFTM (θJA) ...........................................41.7°C/W

Electrical Characteristics(4)

fRF = 915MHz. Data-rate = 125kbps, Modulation type = closed-loop VCO modulation, VDD = 2.5V; TA = 25°C, bold

values indicate –40°C< TA < +85°C, unless noted.

Symbol Parameter Condition Min Typ Max Units

RF Frequency Operating

Range

850 950 MHz

Power Supply 2.25 5.5 V

Power Down Current 0.3 2 µA

Standby Current 370

µA

Low Voltage Dropout regulator

Output Voltage 2.5

Turn-On Time 30

µS

VCO and PLL Section

Reference Frequency 4 40

MHz

915MHz to 915.5MHz 0.5 ms PLL Lock Time(5)

3kHz bandwidth 902MHz to 927MHz 1.7 ms

PLL Lock Time(5)

20kHz bandwidth

915MHz to 915.5MHz 0.3 ms

Rx – Tx 0.6 ms

Tx – Rx 0.6 ms

Standby Rx 1.1 ms

Switch Time(5)

3kHz loop bandwidth

Standby Tx 1.2 ms

Crystal Oscillator Start-Up

Time

16MHz, 9pF load, 5.6pF loading

capacitors

1.2 ms

VCPOUT = 1.1V, CP_HI = 0 125 µA

Charge Pump Current VCPOUT = 1.1V, CP_HI = 1 500 µA

Transmit Section

RLOAD = 50Ω, Pa2-0-111 10 dBm Output Power

RLOAD = 50Ω, Pa2-0-001 -8 dBm

Over temperature range 2 dB Output Power Tolerance Over power supply range 3 dB

RLOAD = 50Ω, Pa2-0-111 28 mA Tx Current Consumption RLOAD = 50Ω, Pa2-0-001 14 mA

Binary FSK Frequency

Separation(5)

Birate = 200kbps 20 500

kHz

VCO modulation 20 200

kbps Data Rate(5) Divider modulation 20

kbps

38.4kbps, β = 2, 20dBc kHz Occupied bandwidth(5)

125kbps, β = 2, 20dBc kHz

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Symbol Parameter Condition Min Typ Max Units

200kbps, β = 2, 20dBc kHz

Spurious Emission < 1GHz(5)

-57 dBm

Spurious Emission > 1GHz(5)

ETSI EN300 220

(Using antenna matching network)

-47 dBm

nd Harmonic (5)

-20 dBc

rd Harmonic(5)

-41.2 dBm

Spurious Emission <902MHz -49.2 dBm

Spurious Emission >928MHz

FCC part 15, RLoad 50Ω

(Using antenna matching network)

-41.2 dBm

Receive Section

All functions turned on 13.5 mA

LNA bypass 10.9 mA

Switch cap filter bypass with LNA 10.9 mA

Rx Current Consumption

Bypass of Switch cap and LNA 8.6 mA

Rx Current Consumption

Variation

Over temperature 4 mA

2.4kbps, β = 16, SC=50kHz, BER

10-3

-111 dBm

4.8kbps, β = 16, SC=50kHz, BER

10-3

-110 dBm

19.2kbps, β = 8, SC=200kHz, BER

10-3

-107 dBm

38.4kbps, β = 4, BER 10-3 -104 dBm

76.8kbps, β = 2, BER 10-3 -101 dBm

125kbps, β = 2, BER 10-3 -100 dBm

Receiver Sensitivity

200kbps, β = 2, BER 10-3 -97 dBm

125kbps, β = 2 -12 dBm Receiver Maximum Input

Power 20kbps, β = 10 -10 dBm

Over temperature 4 dB Receiver Sensitivity Tolerance Over power supply range 1 dB

Receiver Bandwidth 50 350 kHz

Co-Channel Rejection 19.2 kbps, β = 6, SC=133 kHz dB

500kHz spacing, 19.2kbps, Main

filter cut off frequency 133kHz

Adjacent Channel Rejection 1MHz ,19.2kbps, Main filter cut off

frequency 133kHz

Offset ±1MHz 55 dB

Offset ±2MHz 58 dB

Offset ±5MHz 48 dB

Offset ±10MHz 50 dB

Blocking

Desired signal:

19.2 kbps, β

=6, 3dB above

sens, SC=133

kHz

Offset ±30MHz 60 dB

1dB Compression -34 dBm

Input IP3 2 tones with 1MHz separation -25 dBm

LO Leakage -90 dBm

<1GHz, EN 300 220 -57 dBm Spurious Emission(5) >1GHz, EN 300 220 -47 dBm

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Symbol Parameter Condition Min Typ Max Units

Input Impedance(5) 50

Ω

RSSI Dynamic Range 50 dB

Pin = -110dBm 0.9 V RSSI Output Range Pin = -60dBm 2 V

Digital Inputs/Outputs

VIH Logic Input High 0.7x

VDDout

2.5 V

VIL Logic Input Low 0 0.3x

VDDou

Clock/Data Frequency(5) 10 MHz

Clock/Data Duty Cycle(5) 45 55 %

LDO Enable input Voltage Logic Low (LDO Shutdown) 0.2 V

Logic High (LDO Enabled) 1 V

LDO Enable input current VIL≤0.2V (LDO Shutdown) 0.01 1 µA

VIH≤1.0V (LDO Enabled) 0.01 1 µA

Notes:

1. Exceeding the absolute maximum rating may damage the device.

2. The device is not guaranteed to function outside its operating rating.

3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.

4. Specification for packaged product only.

5. Guaranteed by design.

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Programming

General

The MICRF505 functions are enabled through a

number of programming bits. The programming bits

are organized as a set of addressable control

registers, each register holding 8 bits.

There are 23 control registers in total in the

MICRF505, and they have addresses ranging from 0

to 22. The user can read all the control registers.

The user can write to the first 22 registers (0 to 21);

the register 22 is a read-only register.

All control registers hold 8 bits and all 8 bits must be

written to when accessing a control register, or they

will be read. Some of the registers do not utilize all 8

bits. The value of an unused bit is “don’t care.”

The control register with address 0 is referred to as

ControlRegister0, the control register with address 1

is ControlRegister1 and so on. A summary of the

control registers is given in the table below. In

addition to the unused bits (marked with”-“) there are

a number of mandatory bits (marked with “0” or “1”).

Always maintain these as shown in the table.

The control registers in MICRF505 are accessed

through a 3-wire interface; clock, data and chip

select. These lines are referred to as SCLK, IO, and

CS, respectively. This 3-wire interface is dedicated

to control register access and is referred to as the

control interface. Received data (via RF) and data to

transmit (via RF) are handled by the DataIXO and

DataClk (if enabled) lines; this is referred to as the

data interface.

The SCLK line is applied externally; access to the

control registers are carried out at a rate determined

by the user. The MICRF505 will ignore transitions on

the SCLK line if the CS line is inactive. The

MICRF505 can be put on a bus, sharing clock and

data lines with other devices.

All control registers should be written to after a

battery reset. During operation, it is sufficient to write

to one register only. The MICRF505 will

automatically enter power down mode after a battery

reset.

Adr Data

A6…A0 D7 D6 D5 D4 D3 D2 D1 D0

0000000 LNA_by PA2 PA1 PA0 Sync_en Mode1 Mode0 Load_en

0000001 Modulation1 Modulation0 ‘0’ ‘0’ RSSI_en LD_en PF_FC1 PF_FC0

0000010 CP_HI SC_by ‘0’ PA_By OUTS3 OUTS2 OUTS1 OUTS0

0000011 ‘1’ ‘1’ ‘0’ VCO_IB2 VCO_IB1 VCO_IB0 VCO_freq1 VCO_freq0

0000100 Mod_F2 Mod_F1 Mod_F0 Mod_I4 Mod_I3 Mod_I2 Mod_I1 Mod_I0

0000101 - - ‘0’ ‘1’ Mod_A3 Mod_A2 Mod_A1 Mod_A0

0000110 - Mod_clkS2 Mod_clkS1 Mod_clkS0 BitSync_clkS2 BitSync_clkS1 BitSync_clkS0 BitRate_clkS2

0000111 BitRate_clkS1 BitRate_clkS0 RefClk_K5 RefClk_K4 RefClk_K3 RefClk_K2 RefClk_K1 RefClk_K0

0001000 ‘1’ ‘1’ ScClk5 ScClk4 ScClk3 ScClk2 ScClk1 ScClk0

0001001 ‘0’ ‘0’ ‘1’ XCOtune4 XCOtune3 XCOtune2 XCOtune1 XCOtune0

0001010 - - A0_5 A0_4 A0_3 A0_2 A0_1 A0_0

0001011 - - - - N0_11 N0_10 N0_9 N0_8

0001100 N0_7 N0_6 N0_5 N0_4 N0_3 N0_2 N0_1 N0_0

0001101 - - - - M0_11 M0_10 M0_9 M0_8

0001110 M0_7 M0_6 M0_5 M0_4 M0_3 M0_2 M0_1 M0_0

0001111 - - A1_5 A1_4 A1_3 A1_2 A1_1 A1_0

0010000 - - - - N1_11 N1_10 N1_9 N1_8

0010001 N1_7 N1_6 N1_5 N1_4 N1_3 N1_2 N1_1 N1_0

0010010 - - - - M1_11 M1_10 M1_9 M1_8

0010011 M1_7 M1_6 M1_5 M1_4 M1_3 M1_2 M1_1 M1_0

0010100 ‘1’ ‘0’ ‘1’ ‘1’ ‘0’ ‘1’ ‘0’ ‘1’

0010101 - - - - FEEC_3 FEEC_2 FEEC_1 FEEC_0

0010110 FEE_7 FEE_6 FEE_5 FEE_4 FEE_3 FEE_2 FEE_1 FEE_0

Names of programming bits, unused bits (“-“) and mandatory bits (“1” or “0”) are shown. Change of mandatory bits may cause malfunction.

Table 1. Control Registers in MICRF505

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Writing to the control registers in MICRF505

Writing: A number of octets are entered into

MICRF505 followed by a load-signal to activate the

new setting. Making these events is referred to as a

“write sequence.” It is possible to update all, 1, or n

control registers in a write sequence. The address to

write to (or the first address to write to) can be any

valid address (0-21). The IO line is always an input

to the MICRF505 (output from user) when writing.

What to write:

• The address of the control register to write

to (or if more than 1 control register should

be written to, the address of the 1st control

• A bit to enable reading or writing of the

control registers. This bit is called the R/W

bit.

• The values to write into the control

What to write:

Field Comments

Address: A 7-bit field, ranging from 0 to 21. MSB is

written first.

R/W bit: A 1-bit field, = “0” for writing

Values: A number of octets (1-22 octets). MSB in

every octet is written first. The first octet is

written to the control register with the

specified address (=”Address”). The next

octet (if there is one) is written to the control

on.

Table 2.

How to write:

Bring CS active to active to start a write sequence.

The active state of the CS line is “high.” Use the

SCLK/IO serial interface to clock “Address” and

“R/W” bit and “Values” into the MICRF505.

MICRF505 will sample the IO line at negative edges

of SCLK. Make sure to change the state of the IO

line before the negative edge. Refer to figures

below.

Bring CS inactive to make an internal load-signal

and complete the write-sequence. Note: there is an

exception to this point. If the programming bit called

“load_en” (bit0 in ControlRegister0) is “0”, then no

load pulse is generated.

The two different ways to “program the chip” are:

• Write to a number of control registers (0-22)

when the registers have incremental

addresses (write to 1, all or n registers)

• Write to a number of control registers when

the registers have non-incremental

addresses.

Writing to a Single Registe r

Writing to a control register with address “A6. A5,

…A0” is described here. During operation, writing to

1 register is sufficient to change the way the

transceiver works. Typical example: Change from

receive mode to power-down.

What to write:

Field Comments

Address: 7 bit = A6, A5, …A0 (A6 = msb. A0 = lsb)

R/W bit: “0” for writing

Values: 8 bits = D7, D6, …D0 (D7 = msb, D0 = lsb)

Table 3.

“Address” and “R/W bit” together make 1 octet.

In addition, 1 octet with programming bits is entered. In

total, 2 octets are clocked into the MICRF505.

How to write:

• Bring CS high

• Use SCLK and IO to clock in the 2 octets

• Bring CS low

SCLK

IO A6 A5 A0 RW D7 D6 D2 D1 D0

Address of register i RW Data to write into register i

Internal load pulse made here

Figure 1.

In Figure 1, IO is changed at positive edges of SCLK. The

MICRF505 samples the IO line at negative edges. The

value of the R/W bits is always “0” for writing.

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Writing to All Registers

After a power-on, all writable registers should be

written. This is described here.

Writing to all register can be done at any time. To

get the simplest firmware, always write to all

registers. The price to pay for the simplicity is

increased write-time, which leads to increased time

to change the way the MICRF505 works.

What to write

Field Comments

Address: ‘000000’ (address of the first register to write

to, which is 0)

R/W bit: “0” for writing

Values: 1st Octet: wanted values for

ControlRegister0. 2nd Octet: wanted values

for ControlRegister1 and so on for all of the

octets. So the 22nd octet wants values for

ControlRegister21. Refer to the specific

sections of this document for actual values.

Table 4.

“Address” and “R/W bit” together make 1 octet.

In addition, 22 octets with programming bits are entered.

In total, 23 octets are clocked into the MICRF505.

How to write:

• Bring CS high

• Use SCLK and IO to clock in the 23 octets

• Bring CS low

Refer to the figure in the next section, “Writing to n

registers having incremental addresses”.

Writing to n Registers having Incremental

Addresses

In addition to entering all bytes, it is also possible to

enter a set of n bytes, starting from address i = “A6,

A5, … A0”. Typical example: Clock in a new set of

frequency dividers (i.e. change the RF frequency).

“Incremental addresses”. Registers to be written are

located in i, i+1, i+2.

What to write

Field Comments

Address: 7 bit = A6, A5, …A0 (A6 = msb. A0 = lsb)

(address of first byte to write to)

R/W bit: “0” for writing

Values: n* 8 bits =

D7, D6, …D0 (D7 = msb, D0 = lsb) (written

to control reg. with address ”i”)

D7, D6, …D0 (D7 = msb, D0 = lsb) (written

to control reg. with address ”i+1”)

D7, D6, …D0 (D7 = msb, D0 = lsb) (written

to control reg. with address ”i+n-1”)

Table 5.

“Address” and “R/W bit” together make 1 octet.

In addition, n octets with programming bits are entered.

Totally, 1 +n octets are clocked into the MICRF505.

How to write:

• Bring CS high

• Use SCLK and IO to clock in the 1 + n

octets

• Bring CS low

In Figure 1, IO is changed at positive edges of SCLK. The

MICRF505 samples the IO line at negative edges. The

value of the R/W bits is always “0” for writing.

SCLK

IO A6 A5 A0 RW D7 D6 D2 D1 D0

Address of first RW

Data to write

into register i

Internal load pulse made here

Data to write

into register i+1

Figure 2.

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Writing to n Registers having Non-Incremental

Addresses

Registers with non-incremental addresses can be

written to in one write-sequence as well. Example of

non-incremental addresses: “0,1,3”. However, this

requires more overhead, and the user should

consider the possibility to make a “continuous”

update, for example, by writing to “0,1,2,3” (writing

the present value of “2” into “2”). The simplest

firmware is achieved by always writing to all

registers. Refer to previous sections.

This write-sequence is divided into several sub-

parts:

• Disable the generation of load-signals by

clearing bit “load_en” (bit0 in

ControlRegister0)

• Repeat for each group of register having

incremental addresses:

o Bring CS active

o Enter first address for this group,

R/W bit and values

o Bring CS inactive

o Finally, enable and make a load-

signal by setting “load_en”

Refer to the previous sections for how to write to 1 or

n (with incremental addresses) registers in the

MICRF505.

Reading from the control registers in MICRF505

The “read-sequence” is:

1. Enter address and R/W bit

2. Change direction of IO line

3. Read out a number of octets and change IO

direction back again.

It is possible to read all, 1 or n registers. The

address to read from (or the first address to read

from) can be any valid address (0-22). Reading is

not destructive, i.e. values are not changed. The IO

line is output from the MICRF505 (input to user) for a

part of the read-sequence. Refer to procedure

description below.

A read-sequence is described for reading n

registers, where n is number 1-23.

Reading n registers from MICRF505

SCLK

IO A6 A5 A0 RW D7 D6 D0

Address of register i RWData read from reg. i

imple time

O Input

O Output

Figure 3.

In the figure, 1 register is read. The address is A6,

A5, … A0. A6 = msb. The data read out is D7, D6,

…D0. The value of the R/W bit is always “1” for

reading.

SCLK and IO together form a serial interface. SCLK

is applied externally for reading as well as for writing.

• Bring CS active

• Enter address to read from (or the first

address to read from) (7 bits) and

• The R/W bit = 1 to enable reading

• Make the IO line an input to the user (set pin

in tristate)

• Read n octets. The first rising edge of SCLK

will set the IO as an output from the

MICRF505. MICRF will change the IO line at

positive edges. The user should read the IO

line at the negative edges.

• Make the IO line an output from the user

again.

Programming interface timing

Figure 4 and Table 6 shows the timing specification for the 3-wire

serial programming interface.

CLK

OA6 A5 A0 RW D7 D6 D2 D1 D0

Address Register Data Register

LOA

Tscl

Twrite

TreadThigh

Tlow

TperTcsr traise

tfall

Figure 4.

Values

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Symbol Parameter Min. Typ. Max. Units

Tper Min. period of SCLK 50 ns

Thigh Min. high time of SCLK 20 ns

Tlow Min. low time of SCLK 20 ns

tfall Max. time of falling edge of SCLK 1 µs

trise Max. time of rising edge of SCLK 1 µs

Tcsr Max. time of rising edge of CS to falling edge of SCLK 0 ns

Tcsf Min. delay from rising edge of CS to rising edge of

SCLK

5 ns

Twrite Min. delay from valid IO to falling edge of SCLK

during a write operation

0 ns

Tread Min. delay from rising edge of SCLK to valid IO during

a read operation (assuming load capacitance of IO is

25pF)

75 ns

POR Power on Reset delay from voltage is supplied to he

device until POR completed

4.6 9 ms

Table 6. Timing Specification for the 3-wire Programming Interface

Power on Reset

When applying voltage to the MICRF505 a power

on reset state is entered. During the time period of

power on reset, the MICRF505 should be

considered to be in an unknown state and the user

should wait until completed (See Table 6). The

power on reset timing given in table 6 is covering all

conditions and should be treated as a maximum

delay time. In some application it might be beneficial

to minimize the power on reset time. In these cases

we recommend to follow below procedure:

Program

address 0x00

Word:0x03

Read back

programmed

address 0x00

Value=0x03?

End of Power on

Reset

YES

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Programming summary

• Use CS, SCLK, and IO to get access to the

control registers in MICRF505.

• SCLK is user-controlled.

• Write to the MICRF505 at positive edges

(MICRF505 reads at negative edges).

• Read from the MICRF505 at negative edges

(MICRF505 writes at positive edges)

• After power-on: Write to the complete set of

control registers.

• Address field is 7 bits long. Enter msb first.

• R/W bit is 1 bit long (“1” for read, “0” for

write)

• Address and R/W bit together make 1 octet

• All control registers are 8 bits long.

Enter/read msb in every octet first.

• Always write 8 bits to/read 8 bits from a

control register. This is the case for registers

with less than 8 used programming bits as

well.

• Writing: Bring CS high, write address and

R/W bit followed by the new values to fill into

the addressed control register(s) and bring

CS low for loading, i.e. activation of the new

control register values (“load_en” = 1).

• Reading: Bring CS high, write address and

R/W bit, set IO as an input, read present

contents of the addressed control

output.

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Frequency Synthesizer

The MICRF505 frequency synthesizer consists of a

voltage-controlled oscillator (VCO), a crystal

oscillator, dual modulus prescaler, programmable

frequency dividers and a phase-detector. The loop-

filter is external for flexibility and can be a simple

passive circuit. The phase detector compares

frequencies of two signals and produces an error

signal which is proportional to the difference

between the input frequencies. The error signal is

used to control a voltage-controlled oscillator (VCO)

which creates an output frequency. The output

frequency is fed through a frequency divider back to

the input of the phase detector, producing a

feedback loop. If the output frequency drifts, the

error signal will increase, driving the frequency in the

opposite direction so as to reduce the error. Thus

the output is locked to the frequency at the other

input. This input is called the reference and is

derived from a crystal oscillator, which is very stable

in frequency. The block diagram below shows the

basic elements and arrangement of a PLL based

frequency synthesizer. The MICRF505 has a dual

modulus prescaler for increased frequency

resolution. In a dual modulus prescaler the main

divider is split into two parts, the main part N and an

additional divider A, where A < N. Both dividers are

clocked from the output of the dual-modulus

prescaler, but only the output of the N divider is fed

into the phase detector. The prescaler will first divide

by 16. Both N and A count down until A reaches

zero, at which point the prescaler is switched to a

division ratio 16+1. At this point, the divider N has

completed A counts. Counting continues until N

reaches zero, which is an additional N-A counts. At

this point the cycle repeats.

A6…A0 D7 D6 D5 D4 D3 D2 D1 D0

0001010 - - A0_5 A0_4 A0_3 A0_2 A0_1 A0_0

0001011 - - - - N0_11 N0_10 N0_9 N0_8

0001100 N0_7 N0_6 N0_5 N0_4 N0_3 N0_2 N0_1 N0_0

0001101 - - - - M0_11 M0_10 M0_9 M0_8

0001110 M0_7 M0_6 M0_5 M0_4 M0_3 M0_2 M0_1 M0_0

0001111 - - A1_5 A1_4 A1_3 A1_2 A1_1 A1_0

0010000 - - - - N1_11 N1_10 N1_9 N1_8

0010001 N1_7 N1_6 N1_5 N1_4 N1_3 N1_2 N1_1 N1_0

0010010 - - - - M1_11 M1_10 M1_9 M1_8

0010011 M1_7 M1_6 M1_5 M1_4 M1_3 M1_2 M1_1 M1_0

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The lengths of the N, M, and A registers are 12, 12

and 6 respectively The values can be calculated

from the following formula:

()()

A N 16

fRF

XCO

PhD +×

+×

== VCO

M≠0

1 ≤ A < N

where

fPhD: Phase detector comparison frequency

fXCO: Crystal oscillator frequency

fVCO: Voltage controlled oscillator frequency

fRF: RF carrier frequency

There are two sets of each of the divide factors (i.e.

A0 and A1). If modulation by using the dividers is

selected (that is Modulation1=1, Modulation0=0), the

two sets should be programmed to give two RF

frequencies, separated by two times the specified

frequency deviation. For all other modulation

methods, and also in receive mode, the 0-set will be

used.

Crystal Oscillator (XCO)

Adr D7 D6 D5 D4 D3 D2 D1 D0

0001001 ‘0’ ‘0’ ‘1’ XCOtune4 XCOtune3 XCOtune2 XCOtune1 XCOtune0

The crystal oscillator is a very critical block. As the

crystal oscillator is a reference for the RF output

frequency and also for the LO frequency in the

receiver, very good phase and frequency stability is

required. The schematic of the crystal oscillator’s

external components for 16MHz are shown in Figure

C11

5.6pF

C10

5.6pF

TSX-10A

Pin 24

TALOUT Pin 2

XTALI

Figure 5. Crys tal Oscillator Circuit

The crystal should be connected between pins

XTALIN and XTALOUT (pin 23 and 24). In addition,

loading capacitors for the crystal are required. The

loading capacitor values depend on the total load

capacitance, CL, specified for the crystal. The load

capacitance seen between the crystal terminals

should be equal to CL for the crystal to oscillate at

the specified frequency.

CL = 1

C10

C11

+Cparasitic

The parasitic capacitance is the pin input

capacitance and PCB stray capacitance. Typically,

the total parasitic capacitance is around 6pF. For

instance, for a 9pF load crystal the recommended

values of the external load capacitors are 5.6pF.

It is also possible to tune the crystal oscillator

internally by switching in internal capacitance using

5 tune bits XCOtune4 – XCOtun0. When XCOtune4

– XCOtune0 = 0 no internal capacitors are

connected to the crystal pins. When XCOtune4 –

XCOtune0 = 1 all of the internal capacitors are

connected to the crystal pins. Figure 6 shows the

tuning range for two different capacitor values, 1.5pF

and no capacitors.

The crystal used is a TN4-26011 from Toyocom.

Specification: Package TSX-10A, Nominal frequency

16.000000 MHz, frequency tolerance ±10ppm,

frequency stability ±9ppm, load capacitance 9pF,

pulling sensitivity 15ppm/pF. When the external

capacitors are set to 1.5pF and the XCOtune=16,

the total capacitance will normally be ~9pF.

-60,0

-40,0

-20,0

0,0

20,0

40,0

60,0

80,0

100,0

0 8 16 24 32

XCO bitvalue

[ppm]

2x1.5pF

2x0pF

Figure 6. XCO Tuning

The start up time is given in Table 7. As can be

seen, more capacitance will slow down the start up

time.

The start-up time of a crystal oscillator is typically

around a millisecond. Therefore, to save current

consumption, the XCO is turned on before any other

circuit block. During start-up the XCO amplitude will

eventually reach a sufficient level to trigger the M-

counter. After counting 2 M-counter output pulses

the rest of the circuit will be turned on. The current

consumption during the prestart period is

approximately 280µA.

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XCOtune Start-up Time (µs)

0 590

1 590

2 700

4 700

8 810

16 1140

31 2050

Table 7. Typical values with CEXT = 1.5pF

If an external reference is used instead of a crystal,

the signal shall be applied to pin 24, XTALOUT. Due

to internal DC setting in the XCO, an AC coupling is

recommended to be used between the external

reference and the XTALOUT-pin.

VCO

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000011 ‘1’ ‘1’ ‘0’ VCO_IB2 VCO_IB1 VCO_IB0 VCO_freq1 VCO_freq0

The VCO has no external components. If has three

bit to set the bias current and two bit to set the VCO

frequency. These five bit are set by the RF

frequency, as follows:

RF freq. VCO_IB2 VCO_IB1 VCO_IB0 VCO_freq1 VCO_freq0

850MHz 1 1 1 0 0

868MHz 0 1 1 0 1

915MHz 0 0 1 1 0

950MHz 0 0 0 1 1

Table 8. VCO Bit Setting

The bias bit will optimize the phase noise, and the

frequency bit will control a capacitor bank in the

VCO. The tuning range, the RF frequency versus

varactor voltage, is dependent on the VCO

frequency setting, and can be shown in Figure 7.

When the tuning voltage is in the range from 0.9V to

1.4V, the VCO gain is at its maximum, approximately

65-70MHz/V. It is recommended that the varactor

voltage stays in this range.

The input capacitance at the varactor pin must be

taken into consideration when designing the PLL

loop filter. This is most critical when designing a loop

filter with high bandwidth, which gives relatively

small component values. The input capacitance is

approximately 6pF.

Tuning range

800

820

840

860

880

900

920

940

960

980

1000

00.511.522.5

Varactor voltage (V)

Frequency (MHz)

'00'

'01'

'10'

'11'

Figure 7. RF Frequency vs. Varactor Voltage

and VCO Frequency bit (VDD = 2.25V)

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Charge Pump

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000010 CP_HI SC_by ‘0’ PA_by OUTS3 OUTS2 OUTS1 OUTS1

The charge pump current can be set to either 125µA

or 500µA by CP_HI (‘1’ → 500µA). This will affect

the loop filter component values, see “PLL Filter”

section. In most cases, the low current is best suited.

For applications using phase detector frequency and

high PLL bandwidth, the 500µA can be a better

choice.

PLL Filter

The design of the PLL filter will strongly affect the

performance of the frequency synthesizer. The PLL

filter is kept externally for flexibility. Input parameters

when designing the loop filter for the MICRF505 are

mainly the modulation method and the bit rate.

These choices will also affect the switching time and

phase noise.

The frequency modulation can be done in two

different ways with the MICRF505, either by VCO

modulation or by modulation with the internal

dividers (see chapter Frequency modulation for

further details). In the first case, the PLL needs to

lock on a new carrier frequency for every new data

bit. Now the PLL bandwidth needs to be adequately

high. It is recommended to use a third order filter to

suppress the phase detector frequency, as this is

not suppressed as much as when doing modulation

on the VCO with a lower bandwidth filter.

A schematic for a second (R2=0 and C3=NC) and

third order loop filter is shown in Figure 8.

C3C1

Pin 27

P_OUT

Pin 29

VARI

Figure 8. Second and Third Order Loop Filter

Table 9 shows three different loop filters, the two first

for VCO modulation and the last one for modulation

using the internal dividers. The component values

are calculated with RF frequency = 915MHz, VCO

gain = 67MHz/V and charge pump current = 125µA.

Other settings are shown in the table. The varactor

pin capacitance (pin 29) of 5pF does not influence

on the component values for the two filters with

lowest bandwidth.

Baud Rate

(kbaud/sec)

PLL

(kHz)

Phase

Margin(˚)

Phase

Detector

Freq.

(kHz)

C1 C2 R1 R2 C3

VCO >38.4 0.8 56 100 10nF 100nF 6.2kΩ0 NC

VCO >125 3,2 56 100 680pF 6.8nF 22kΩ 0 NC

Divider <20 13 86 500 150pF 10nF 18kΩ 82kΩ4.7pF

Table 9. Loop Filter Components Values

Lock Detect

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000001 Modulation1 Modulation0 ‘0’ ‘0’ RSSI_en LD_en PF_FC1 PF_FC0

A lock detector can be enabled by setting LD_en = 1. When pin

LD is high, it indicates that the PLL is in lock.

Modes of Operation

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000000 LNA_by PA2 PA1 PA0 Sync_en Mode1 Mode0 Load_en

Mode1 Mode0 State Comments

0 0 Power down Keeps register configuration

0 1 Standby Only crystal oscillator running

1 0 Receive Full receive

1 1 Transmit Full transmit ex PA state

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Low Dropout Regulator

The MICRF505LBML/YML has an internal voltage

regulator powering the MICRF505 device. This LDO

is equipped with a logic-compatible enable pin and

can be put into a zero-off-mode current state,

drawing no current when disabled. The LDO is a

µCap design operating with very small ceramic

output capacitors for stability.

Enable/Shutdown

The internal LDO comes with an active-high enable

pin that allows the regulator to be disabled. Forcing

the enable pin low disables the regulator and sends

it into a “zero” off-mode-current

state. In this state, current consumed by the

regulator goes nearly to zero. Forcing the enable pin

high enables the output voltage. The active-high

enable pin uses CMOS technology and the enable

pin cannot be left floating; a floating enable pin may

cause an indeterminate state on the output.

Input Capacitor

The LDO require a well-bypassed input supply for

optimal performance. A 1µF capacitor is required

from the input to ground to provide stability. Low-

ESR ceramic capacitors provide optimal

performance at a minimum of space. Additional high

frequency capacitors, such as small-valued NPO

dielectric-type capacitors, help filter out high-

frequency noise and are good practice in any RF-

based circuit.

Output Capacitor

The LDO require an output capacitor of 1µF or

greater to maintain stability. The design is optimized

for use with low-ESR ceramic chip capacitors. High

ESR capacitors may cause high frequency

oscillation. The output capacitor can be increased,

but performance has been optimized for a 1µF

ceramic output capacitor and does not improve

significantly with larger capacitance. X7R/X5R

dielectric-type ceramic capacitors are recommended

because of their temperature performance. X7R-

type capacitors change capacitance by 15% over

their operating temperature range and are the most

stable type of ceramic capacitors. Z5U and Y5V

dielectric capacitors change value by as much as

50% and 60%, respectively, over their operating

temperature ranges. To use a ceramic chip capacitor

with Y5V dielectric, the value must be much higher

than an X7R ceramic capacitor to ensure the same

minimum capacitance over the equivalent operating

temperature range.

Bypass Capacitor

A capacitor can be placed from the noise bypass pin

to ground to reduce output voltage noise. The

capacitor bypasses the internal reference. A 0.1µF

capacitor is recommended for applications that

require low-noise outputs. The bypass capacitor can

be increased, further reducing noise and improving

PSRR. Turn-on time increases slightly with respect

to bypass capacitance. A unique, quick-start circuit

allows the LDO to drive a large capacitor on the

bypass pin without significantly slowing turn-on time.

Refer to the Typical Characteristics section for

performance with different bypass capacitors.

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Transceiver S ync/Non-Synchronous Mode

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000000 LNA_by PA2 PA1 PA0 Sync_en Mode1 Mode0 Load_en

0000110 - Mod_clkS2 Mod_clkS1 Mod_clkS0 BitSync_clk

BitSync_clk

BitRate_clkS

0000111 BitRate_clkS

BitRate_clkS

RefClk_K5 RefClk_K4 RefClk_K3 RefClk_K2 RefClk_K1 RefClk_K0

Sync_en State Comments

0 Rx: Bit

synchronization off Transparent reception of data

0 Tx: DataClk pin off Transparent transmission of data

1 Rx: Bit

synchronization on Bit-clock is generated by transceiver

1 Tx: DATACLK pin

on Bit-clock is generated by transceiver

When Sync_en = 1, it will enable the bit

synchronizer in receive mode. The bit synchronizer

clock needs to be programmed, see chapter Bit

synchronizer. The synchronized clock will be set out

on pit DATACLK.

In transmit mode, when Sync_en = 1, the clock

signal on pin DATACLK is a programmed bit rate

clock. Now the transceiver controls the actual data

rate. The data to be transmitted will be sampled on

rising edge of DATACLK. The micro controller can

therefore use the negative edge to change the data

to be transmitted. The clock used for this purpose,

BITRATE_CLK, is programmed in the same way as

the modulator clock and the bit synchronizer clock:

)-(7

XCO

KBITRATE_CL 2Refclk_K

f kSBitRate_cl

where:

fBITRATE_CLK: The clock frequency used to

control the bit rate, should be equal to the bit

rate (bit rate of 20 kbit/sec requires a clock

requency of 20kHz)

fXCO: Crystal oscillator frequency

Refclk_K: 6 bit divider, values between 1

and 63

BitRate_clkS: Bit rate setting, values

between 0 and 6

Data Interface

The MICRF505 interface can be divided in to two

separate interfaces, a “programming interface” and a

“Data interface”. The “programming interface” has a

three wire serial programmable interface and is

described in chapter Programming.

The “data interface” can be programmed to sync-

/non-synchronous mode. In synchronous mode the

MICRF505 is defined as “Master” and provides a

data clock that allows users to utilize low cost micro

controller reference frequency.

The data interface is defined in such a way that all

user actions should take place on falling edge and is

illustrated Figure 9 and 10. The two figures illustrate

the relationship between DATACLK and DATAIXO

in receive mode and transmit mode.

MICRF505 will present data on rising edge and the

“USER” sample data on falling edge in receive

mode.

DATAIXO

DATACLK

Figure 10. Data interface in Receive Mode

The User presents data on falling edge and

MICRF505 samples on rising edge in transmit mode.

DATAIXO

DATACLK

Figure 11. Data interface in Transmit Mode

When entering transmit mode it is important to keep

DATAIXO in tri-state from the time Tx-mode is

entered until user starts sending data. The data is

provided directly to the modulation circuit and

violation of this may/will cause abnormal behavior.

Depending upon the chosen FSK modulation, some

sort of encoding might be needed. The different

modulation types and encoding is described in

chapter Frequency modulation.

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Receiver

The receiver is a zero intermediate frequency (IF)

type in order to make channel filtering possible with

low-power integrated low-pass filters. The receiver

consists of a low noise amplifier (LNA) that drives a

quadrature mixer pair. The mixer outputs feed two

identical signal channels in phase quadrature. Each

channel include a pre-amplifier, a third order Sallen-

Key RC lowpass filter from strong adjacent channel

signals and finally a limiter. The main channel filter is

a switched-capacitor implementation of a six-pole

elliptic lowpass filte. The elliptic filter minimizes the

total capacitance required for a given selectivity and

dynamic range. The cut-off frequency of the Sallen-

Key RC filter can be programmed to four different

frequencies: 100kHz, 150kHz, 230kHz and 340kHz.

The demodulator demodulates the I and Q channel

outputs and produces a digital data output. If detects

the relative phase of the I and Q channel signal. If

the I channel signal lags the Q channel, the FSK

tone frequency lies above the LO frequency (data

‘1’). If the I channel leads the Q channel, the FSK

tone lies below the LO frequency (data ‘0’). The

output of the receiver is available on the DataIXO

pin. A RSSI circuit (receive signal strength indicator)

indicates the received signal level.

Front End

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000000 LNA_by PA2 PA1 PA0 Sync_en Mode1 Mode0 Load_en

A low noise amplifier in RF receivers is used to

boost the incoming signal prior to the frequency

conversion process. This is important in order to

prevent mixer noise from dominating the overall

front-end noise performance. The LNA is a two-

stage amplifier and has a nominal gain of

approximately 23dB at 900MHz. The front end has a

gain of about 33dB to 35dB. The gain varies by 1-

1.5dB over a 2.0V to 2.5V variation in power supply.

The LNA can be bypassed by setting bit LNA_by to

‘1’. This can be useful for very strong input signal

levels. The front-end gain with the LNA bypassed is

about 9-10dB. The mixers have a going of about

10dB at 915MHz. The differential outputs of the

mixers can be made available at pins IchOut and

QchOut. The output impedance of each mixer is

about 8kΩ.

The input impedance is close to 50Ω as shown in

Figure 12, giving an input reflection of about -20dB.

The receiver does not require any matching network

to optimize the gain. However, a matching network is

recommended for harmonic suppression in Tx and

for improved selectivity in Rx.

Figure 12. LNA Input Impedance

Sallen-Key Filters

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000001 Modulation1 Modulation0 ‘0’ ‘0’ RSSI_en LD_en PF_FC1 PF_FC0

Each channel includes a pre-amplifier and a prefilter,

which is a three-pole Sallen-Key lowpass filter. It

protects the following switched-capacitor filter from

strong adjacent channel signals, and it also works as

an anti-aliasing filter. The preamplifier has a gain of

22-23dB. The maximum output voltage swing is

about 1.4Vpp for a 2.25V power supply. In addition,

the IF amplifier also performs offset cancellation.

Gain varies by less than 0.5dB over a 2.0 – 2.5V

variation in power supply. The third order Sallen-Key

lowpass filter is programmable to four different cut-

off frequencies according to the table below:

PF_FC1 PF_ F C0 Cut-off Freq. (kHz)

0 0 100

0 1 150

1 0 230

1 1 340

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Switched Capacitor Filter

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0001000 ‘1’ ScClk_X2 ScClk5 ScClk4 ScClk3 ScClk2 ScClk1 ScClk0

The main channel filter is a switched-capacitor

implementation of a six-pole elliptic low pass filter.

The elliptic filter minimized the total capacitance

required for a given selectivity and dynamic range.

The cut-off frequency of the switched-capacitor filter

is adjustable by changing the clock frequency.

The clock frequency is designed to be 20 times the

cut-off frequency. The clock frequency is derived

from the reference crystal oscillator. A

programmable 6-bit divider divides the frequency of

the crystal oscillator. To generate the correct non-

overlapping clock-phases needed by the filter this

frequency is then divided by 4. The cut-off frequency

of the filter is given by:

fCUT = fXCO

40 ⋅ScClk

fCUT: Filter cutoff frequency

fXCO: Crystal oscillator frequency

ScClk: Switched capacitor filter clock, bits

ScClk5-0

For instance, for a crystal frequency of 16MHz and if

the 6 bit divider divides the input frequency by 4 the

cut-off frequency of the SC filter is 16MHz/(40 x 4) =

100kHz. 1st order RC low pass filters are connected

to the output of the SC filter-to-filter the clock

frequency.

The lowest cutoff frequency in the pre- and the main

channel filter must be set so that the received signal

is passed with no attenuation, which is frequency

deviation plus modulation. If there are any frequency

offset between the transmitter and the receiver, this

must also be taken into consideration. A formula for

the receiver bandwidth can be summarized as

follows:

2 / Baudrate f f f DEVOFFSETBW +++=

where

fBW: Needed receiver bandwidth, fcut above

should not be smaller than fBW [Hz]

fOFFSET: Total frequency offset between

receiver and transmitter [Hz]

fDEV: Single-sided frequency deviation, see

chapter Modulator on how to calculate [Hz]

Baudrate: The baud rate given is bit/sec

RSSI

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000001 Modulation1 Modulation0 ‘0’ ‘0’ RSSI_en LD_en PF_FC1 PF_FC0

RSSI

33kohm, 1nF, 125kbps, BW=200kHz, Vdd=2.5V

0.6

0.8

1.2

1.4

1.6

1.8

2.2

-125 -115 -105 -95 -85 -75 -65 -55 -45 -35 -25

Pin [dBm]

RSSI [V]

Figure 13. RSSI Voltage

C10

1nF

33k

Pin 14

RSSI RS

Figure 14. RSSI Network

A Typical plot of the RSSI voltage as function of

input power is shown in Figure 13. The RSSI has a

dynamic range of about 50dB from about -110dBm

to -60dBm input power.

The RSSI can be used as a signal presence

indicator. When a RF signal is received, the RSSI

output increases. This could be used to wake up

circuitry that is normally in a sleep mode

configuration to conserve battery life.

Another application for which the RSSI could be

used is to determine if transmit power can be

reduced in a system. If the RSSI detects a strong

signal, if could tell the transmitter to reduce the

transmit power to reduce current consumption.

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FEE

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0010101 - - - - FEEC_3 FEEC_2 FEEC_1 FEEC_0

0010110 FEE_7 FEE_6 FEE_5 FEE_4 FEE_3 FEE_2 FEE_1 FEE_0

The Frequency Error Estimator (FEE) uses

information from the demodulator to calculate the

frequency offset between it’s receive frequency and

the transmitter frequency. The output of the FEE can

be used to tune the XCO frequency, both for

production calibration and for compensation for

crystal temperature drift and aging.

The inputs to the FEE circuit are the up and down

pulses from the demodulator. Every time a ‘1’ is

updated, an UP-pulse is coming out of the

demodulator, and the same with the DN-pulse every

time the ‘0’ is updated. The expected number of

pulses for every received symbol is 2 times the

modulation index (∆).

The FEE can operate in three different modes;

counting only UP-pulses, only DN-pulses or counting

UP+DN pulses. The number of received symbols to

be counted is either 8, 16, 32 or 64. This is set by

the FEEC_0…FEEC_3 control bit, as follows:

FEEC_1 FEEC_0 FEE Mode

0 0 Off

0 1 Counting UP pulses

1 0 Counting DN pulses

1 1 Counting UP and DN pulses. UP increments

the counter, DN decrements it.

FEEC_3 FEEC_2 No. of symbo ls used for the measur em en t

0 0 8

0 1 16

1 0 32

1 1 65

Table 10. FEEC Control Bit

The result of the measurement is the FEE value, this

can be read from register with address 0010110b.

Negative values are stored as a binary no between

0000000 and 1111111. To calculate the negative

value, a two’s complement of this value must be

performed. Only FEE modes where DN-pulses are

counted (10 and 11) will give a negative value.

When the FEE value has been read, the frequency

offset can be calculated as follows:

Mode UP: Foffset = R/(2P)x(FEE-∆Fp)

Mode DN: Foffset = R/(2P)x(FEE+∆Fp)

Mode UP+DN: Foffset = R/(4P)x(FEE)

where FEE is the value stored in the FEE register,

(Fp is the single sided frequency deviation, P is the

number of symbols/data bit counted and R is the

symbol/data rate. A positive Foffset means that the

received signal has a higher frequency than the

receiver frequency. To compensate for this, the

receivers XCO frequency should be increased (see

ANNEX A) on how to tune the XCO frequency based

on the FEE value).

It is recommended to use Mode UP+DN for two

reasons, you do not need to know the actual

frequency deviation and this mode gives the best

accuracy.

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Bit Synchronizer

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000110 - ModclkS2 ModclkS1 ModclkS0 BitSync_clkS2 BitSync_clkS1 BitSync_clkS0 BitRate_clkS2

0000111 BitRate_clkS1 BitRate_clkS0 RefClk_K5 RefClk_K4 RefClk_K3 RefClk_K2 RefClk_K1 RefClk_K0

A bit synchronizer can be enabled in receive mode

by selecting the synchronous mode (Sync_en=1).

The DataClk pin will output a clock with twice the

frequency of the bit rate (a bit rate of 20 kbit/sec

gives a DataClk of 20 kHz). A received symbol/bit on

DataIXO will be output on rising edge of DataClk.

The micro controller should therefore sample the

symbol/bit on falling edge of DataClk.

The bit synchronizer uses a clock which needs to be

programmed according to the bit rate. The clock

frequency should be 16 times the actual bit rate (a

bit rate of 20 kbit/sec needs a bit synchronizer clock

with frequency of 320 kHz). The clock frequency is

set by the following formula:

fBITSYNC_CLK = fXCO

Refclk_K × 2(7-

BITSYNC_clkS

)

where

fBITSYNC_CLK: The bit synchronizer clock

frequency (16 times higher than the bit rate)

fXCO: Crystal oscillator frequency

Refclk_K: 6 bit divider, values between 1 and

BitSync_clkS: Bit synchronizer setting, values

between 0 and 7

Refclk_K is also used to derive the modulator clock

and the bit rate clock.

At the beginning of a received data package, the bit

synchronizer clock frequency is not synchronized to

the bit rate. When these two are maximum offset to

each other, it takes 22 bit/symbols before

synchronization is achieved.

Micrel MICRF505

MLF and MicroLead Frame is a registered trademark of Amkor Technologies

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

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Transmitter

Power Amplifier

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000000 LNA_by PA2 PA1 PA0 Sync_en Mode1 Mode0 Load_en

0000001 Modulation1 Modulation0 ‘0’ ‘0’ RSSI_en LD_en PF_FC1 PF_FC0

0000010 CP_HI SC_by ‘0’ PA_By OUTS3 OUTS2 OUTS1 OUTS0

The maximum output power is approximately 10dBm

for a 50Ω load. For maximum output power the load

seen by the PA must be resistive. Higher output

power can be obtained by decreasing the load

impedance. However, this will be in conflict with

obtaining impedance match in the LNA. The output

power is programmable in seven steps, with

approximately 3dB between each step. This is

controlled by bits PA2 – PA0.

The power amplifier can be turned off by setting PA2

– PA0 = 0.

For all other combinations the PA is on and has

maximum power when PA2 – PA0 = 1.

The PA will be bypassed if PA_by=1. Output power

will drop ~22dB. It is still possible to control the

power by PA2 – PA0.

The output power varies about 3dB over power

supply 2.0V to 2.5V and about 2dB over temperature

-40˚C to +85˚C. The 2nd and 3rd harmonic of the PA

are as follows:

2nd harmonic: <-16dBm

3rd harmonic: <-8dBm

To reduce the emission of harmonics, an LC filter

can be added between the ANT pin and the antenna

as shown in Figure 15.

ANT

50ohm line 50ohm line

3p3

2p2

8n7

8p2

Figure 15. LC Filter

This filter is designed for the 915MHz band with 50Ω

terminations. The component values may have to be

tuned to compensate for the layout parasitics. This

filter may also increase the receiver selectivity.

Frequency Modulation

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000001 Modulation1 Modulation0 ‘0’ ‘0’ RSSI_en LD_en PF_FC1 PF_FC0

Modulation1 Modulation0 Modulation Type

0 0 Closed loop modulation

using modulator

0 1 Not in use

1 0 FSK applied using two

sets of dividers

1 1 Not in use

Table 11. Modulation Bit Setting

When Modulation1 and Modulation0 is 00, the

modulator needs to be programmed properly, see

“Modulator” section. The modulation signal will now

be applied directly on the phase locked VCO. It is

therefore important that the PLL bandwidth is not too

high, as this will remove the modulation. See “PLL

Filter” section on how to calculate the PLL

components. When using the modulator the

modulation signal is applied to the VCO and

therefore some sort of encoding is needed.

The level of encoding is determined by the PLL loop

filter bandwidth and data rate. Two of the most

common encoding techniques are Manchester

encoding and 3B4B. Other encoding schemes may

also be used.

Manchester encoding is when one bit is encoded in

to a two-bit word and is shown in Table 10. When

using Manchester encoding the maximum overhead

is 100%. When selecting PLL loop filter it is

important to note that the min baud rate is equal to:

baud_min = baud /s

fbaud_min: The minimum frequency of the baud

rate [Hz]

baud/s: Elements per second (encoded data)

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Data Word

“0” “10”

“1” “01”

Table 12. Manchester Encod ing

Another much more efficient encoding type is 3B4B

where three data bits are encoded into a four-bit

word. The reason for encoding is to minimize the DC

component in the modulated data. To have minimum

DC component each four bit word should include

two elements of “1” and two elements of “0”.

Following this guidance only 6 out of 8 word

complies and two encoded words needs special

precaution. Whenever 000 and 111 data appear, the

user must set/clear a flag that indicate if last

encoded word was “Word A” and select the

respective encoded word shown in Table 11.

Data Word A Word B

000 1011 0100

001 1100

010 0011

011 1010

100 0101

101 1001

110 0110

111 1101 0010

Table 13. 3B4B Encoding

When Modulation1 Modulation0 is 10, two sets of

divider values need to be programmed. The formula

for calculating the M, N and A values is given in

chapter Frequency synthesizer. The divider values

stored in the M0-, N0-, and A0- registers will be used

when transmitting a ‘0’ and the M1-, N1-, and A1-

registers will be used to transmit a ‘1’. The difference

between the two carrier frequencies corresponds to

the double sided frequency modulation. Opposite

from the modulation with the modulator, the PLL

shall now lock on a new frequency for every change

in the transmitted data. The PLL bandwidth therefore

needs to be relatively high, higher bit rate requires a

higher PLL bandwidth and vice versa. The data to

be transmitted shall be applied to pin DataIXO (see

chapter Transceiver sync-/non-synchronous mode

on how to use the pin DataClk). The DataIXO pin is

set as input in transmit mode and output in receive

mode. When set as input, a weak voltage divider will

set the level to Vdd/2, when it is not pulled up or

down by the controller. When using the modulator, it

is important that the DataIXO is kept tristated until

the transmission shall begin (when PLL is in lock

and the PA is turned on). When Data IXO is

tristated, the PLL will lock on the LO frequency

(used in receive mode). When DataIXO is set either

high or low, the RF frequency will be shifted up or

down, centered around the LO-frequency. This is

only important when using the modulator, for the

other modulation method, if DATAIXO is tristated,

the M0-, N0- and A0-registers will be used.

Data bits Encoded words Comments

000 000 000 000 000 1011 0100 1011 0100 1011 A Flag indicates if “Word A” has been used

111 111 010 110 000 1101 0010 0011 0110 1011 A Flag indicates if “Word A” has been used

Table 14. Example of 3B4B encoding

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Modulator

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000100 Mod_F2 Mod_F1 Mod_F0 Mod_I4 Mod_I3 Mod_I2 Mod_I1 Mod_I0

0000101 - - ‘0’ ‘1’ Mod_A3 Mod_A2 Mod_A1 Mod_A0

0000110 - Mod_clkS2 Mod_clkS1 Mod_clkS0 BitSync_clkS2 BitSync_clkS1 BitSync_clkS0 BitRate_clkS2

0000111 BitRate_clkS1 BitRate_clkS0 RefClk_K5 RefClk_K4 RefClk_K3 RefClk_K2 RefClk_K1 RefClk_K0

The modulator will create a waveform with

programmable amplitude and frequency. This

waveform is fed into a modulation varactor in the

VCO, which will create the desired frequency

modulation. The frequency spectrum can be

narrowed by increasing the rise-and fall times of the

waveform.

The modulator waveform is created by charging and

discharging a capacitor. A modulator clock controls

the timing, as shown in Figure19. For every rise-and

fall edge, 4 clock periods are being used. The

charging current during these 4 clock periods are not

equal, this is to reduce the high frequency

components in the waveform, which in turn will

narrow the frequency spectrum.

The frequency deviation can be set in three different

ways, as will be explained below. A formula for

setting the desired deviation is given at the end of

this chapter.

odulator Clock

odulator Waveform

Figure 19. Modulator Waveform and Clock

Modulator Clock

The modulator clock frequency is set by:

)(7

XCO

MOD_CLK 2Refclk_K

f Mod_clkS−

where fMOD_CLK is the modulator clock shown in

Figure 19, fXCO is the crystal oscillator frequency

Refclk_K is a 6 bit number and Mod_clkS is a 3 bit

number. Mod_clkS can be set to a value between 0

and 7. The modulator clock frequency should be set

according to the bit rate and shaping.

Mod_clka

Mod_clkb

od_clkb > Mod_clka

Figure 20. Two Different Modulator Clock Setting

A fMOD_CLK of 8 times the bit rate (as in Figure 20)

corresponds to a signal filtered in a Gaussian filter

with a Bandwidth Period product (BT) of 1. When BT

is increased, the waveform will be less filtered.

Minimum BT is 1 (fMOD_CLK is 8 times the bitrate).

Figure 20 shows two waveforms with BT=1 and

BT=2, i.e. the fMOD_CLK is 8 and 16 times higher than

the bit rate. When changing the BT factor, the

charge-and discharge times will also be changed,

and therefore the frequency deviation, as shown in

Figure 19.

Modulator Current

The current used during the rise- and fall times can

be programmed with the Mod_I4..Mod_I0 bit, the

last one being LSB. Figure 21 shows two waveforms

generated with two different currents, where

IbModIaMod __ > . Higher current will give a

higher frequency deviation and vice versa. The

effect of modulator clock and MOD_1 is illustrated

by:

MOD_CLK

DEVIATION f

MOD_1

f ∝

To avoid saturation in the modulator it is important

not to exceed maximum Mod_I. Maximum Mod_I for

a given fMOD_clk is given by:

1-)1028INT(fMOD_I -6

MOD_CLKMAX ×⋅=

where INT() returns the integer part of the argument.

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Mod_la

Mod_lb

od_la > Mod_lb

Figure 21. Two Different Modulator Current Settings

Modulator Attenuator

A third way to set the deviation is by programming

the modulator attenuator, Mod_A2..Mod_A0, the last

being LSB. The purpose of the attenuator is to allow

small deviations when the bit rate is small and/or the

BT is small (these settings will give a relatively slow

modulator clock, and therefore long rise- and fall

times, which in turn results in large frequency

deviations). In addition, the attenuator will improve

the resolution in the modulator.

Mod_Aa

Mod_Ab

od_Ab > Mod_Ab

Figure 22. Two Different Modulator Attenuator

Settings

The effect of the attenuator is given by:

Mod_A1

fDEVIATION +

∝

Figure 22 shows two waveforms with different

attenuator setting: Mod_Ab Mod_Aa <. If Mod_A

is increased, the frequency deviation is lowered and

vice versa.

Modulator Filter

To reduce the high-frequency components in the

generated waveform, a filter with programmable cut-

off frequency can be enabled. This is done using

Mod_F2..Mod_F0, the least one being LSB. The

Mod_F should be set according to the formula:

rate Bit

150x10

MOD_F

Mod_filter on

Mod_filter off

Figure 23. Modulator Waveform with and without

Filtering

Mod_F=0 disables the modulator filter and Mod_F=7

gives most filtering. Figure 23 shows a waveform

with and without the filter.

Calculation of the Frequency Deviation

The parameters influencing the frequency deviation

can be summarized in the following equations:

)(7

XCO

MOD_CLK 2Refclk_K

f Mod_clkS−

()

RF21

MOD_CLK

DEV fCC

Mod_A1

Mod_I

f×+×

×=

Where:

fDEV: Single sided frequency deviation

[Hz]

fXCO: Crystal oscillator frequency [Hz]

fRF: Center frequency [Hz]

Refclk_K: 6 bit divider, values between 1

and 63

Mod_clkS: Modulator clock setting, values

between 0 and 7

fMOD_CLK: Modulator clock frequency,

derived from the crystal

frequency, Refclk_K and

Mod_clkS

Mod_I: Modulator current setting,

values between 0 and 31

Mod_A: Modulator attenuator setting,

values between 0 and 15

C1: --4.42x1010

C2: 72

Micrel MICRF505BML/YML

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The modulator filter will not influence the frequency

deviation as long as the programmed cut-off

frequency is above the actual bit rate.

The frequency deviation must be programmed so

that the modulation index (2 x single sided frequency

deviation/Baudrate [bps]) always is greater than or

equal to 2 including the total frequency offset

between the receiver and the transmitter:

DEV = Baudrate +f

OFFSET

The calculated fDEV should be used to calculate the

needed receiver bandwidth, see chapter Switched

capacitor filter.

Using the XCO-tune Bits

The RF chip has a built-in mechanism for tuning the

frequency of the crystal oscillator and is often used

in combination with the Frequency Error Estimator

(FEE). The XCO tuning is designed to eliminate or

reduce initial frequency tolerance of the crystal

and/or the frequency stability over temperature. If

the value in XCO_tune is increased (adding

capacitance), the frequency will decrease.

The XCO uses two external capacitors (see figure

5). The value of these will strongly affect the tuning

range. With a 16.0 MHz crystal (TN4-26011 from

Toyocom), and external capacitor values of 1.5 pF,

the tuning range will be approximately symmetrical

around the center frequency. A XCO_tune >16 will

decrease the frequency and vice versa (see figure

6).

A procedure for using the XCO_tune feature in

combination with the FEE is given below. The

MICRF505 measures the frequency offset between

the demodulated signal and the LO and tune the

XCO so the LO frequency is equal to received

carrier frequency.

A procedure like this can be called during production

(storing the calibrated XCO_tune value), at regular

intervals or implemented in the communication

protocol when the frequency has changed.

The FEE can count “UP”-pulses and/or “DOWN”-

pulses (pulses out of the demodulator when a logic

“1” or logic “0”, resp.., is received). The FEE can

count pulses for n bits, where n = 8, 16, 32 or 64.

Example: In FEE, count up+down pulses, counting 8

bits:

A perfect case ==> FEE = 0

If FEE > 0: LO is too low, increase LO by decreasing

XCO_tune value

v.v. for FEE < 0

FEE field holds a number in the range -128, … ,

127. However, it keeps counting above/below the

range, which is:

If FEE = -128 and still counting dwn-pulses:

1) =>-129 = +127

2) 126

3) 125

…

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To avoid this situation, always make sure max count

is between limits. Suggestion: Count for 8 (or 16)

bits only.

Procedure description:

In the procedure below, UP+DWN pulses are

counted, and only the sign of the FEE is used. The

value of n is 8 or 16.

Assumption:

A transmitter is sending a 1010… pattern at the

correct frequency and bitrate.

The wanted receiver frequency is the mid-point

between the “0” and “1” frequencies.

Input:

Nothing

Output

The best XCO_tune value (giving the lowest IFEEI)

Local variables:

XCO_Present: (5-bit) holds present value in

XCO_tune bits

XCO_Step: (4-bit) holds increment/decrement of

XCO_tune bits

SCO_Sign: (1 bit) holds POS or NEG

(increment/cerement) increasing LO is done by

reducing the XCO_tune value

XCO TUNE PROCEDURE

INT:

XCO_Present = 0

XCO_Step = 32

XCO_Sign = NEG

Control_Word =

Default RX, clocks match transmitter

LOOP:

XCO_Step = XCO_Step/2

XCO_Sign == POS?

Yes --> XCO_Present- = XCO_Step // increase LO

No --> XCO_Present+ = XCO_Step // decrease LO

XCO_tune bits = CXO_Present

Program RFChip

Delay > n bits

Read FEE

FEE > 0?

Yes --> XCO_Sign = POS

No --> XCO_Sing = NEG // negative or == 0

XCO_Step > 1?

Yes --> Branch to LOOP

No -->

XCO_Sing ==POS?

Yes --> XCO_Present- = 1

Branch to FIN

FIN: RETURN, return-value = XCO_Present

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Typical Application

ANT

RFVDD

RSSI

C12

10n

C11

10n

50ohm line 50ohm line

C13

47p

C10

10n

C14

100nF

C15

LDOen

ASK_DATA

LDOen

PTATBIAS

RFVDD

RFGND

ANT

RFGND

PABIAS

VDDIN

CIBIAS

IFVDD

IFGND

ICHOUT

QCHOUT

RSSI

VDDOUT

LDOBy p 24

Xt a l O u t 23

Xt a lI n 22

CS 21

SCLK 20

IO 19

DATAIXO 18

DATACLK 17

VCOBias 32

VCOVDD 31

VCOGND 30

VARIN 29

GND 28

CP_OUT 27

DIGGND 26

DIGVDD 25

SCLK

DATACLK

DATAIXO

MICRF505LBML

1.5pF

TSX 10A, 16MH z

1 3

3p3pF

2p2F

8n7H

100nF

10nF

R3 18k

82k

33k

6k2

TP1 TP2

8p2F

MICRF505L – MLF32

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MICRF505LBML/YML Land pattern

Figure below shows recommended land pattern. Red circles indicate Thermal/RFGND via’s. Recommended size

is 0.300-0.350mm with a pitch of 1mm. The recommended minimum number of via’s are 9 and they should be

directly connected to ground plane providing the best RF ground and thermal performance. For best yield plugged

or open via’s should be used.

D2'

E2'

D2’ E2’ SD SE d e X Y Units

3.4 ±0.02 3.4 ±0.02 4.2 ±0.05 4.2 ±0.05 0.325 ±0.25 0.5 0.23 ±0.02 0.5 ±0.02 mm

Red circle indicates Thermal Via. Size 0.300-0.350mm

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Layout Considerations

The MICRF505 is a highly integrated RF IC with only a few “hot” pins, however it is suggested to study available

reference design on www.micrel.com before starting with schematics and layout.

• To ensure the best RF design it is important to plan the layout and dedicate area for the different circuitry.

Good RF engineering is to start with the RF circuitry making sure that general RF guidelines are met

(following points). Separate noisy circuitry and RF by placing it on the opposite side maximizing the

distance between the circuitry. The RF circuitry should be placed as close to what is considered the

ground spot (EG battery) to avoid ground currents. Place the RF circuitry in a position that ensure as

short and straight trace to the antenna connection to avoid reflections.

• Proper ground is needed. If the PCB is 2-layer, the bottom layer should be kept only for ground. Avoid

signal traces that split the ground plane. For a 4-layer PCB, it is recommended to keep the second layer

only for ground.

• A ground via should be placed close to all the ground pins. The bottom ground (heat sink) pad should be

penetrated with >9 ground via’s. These via’s should be “open” or “plugged” to avoid air pockets caused by

the solder past. If such air pockets appear, the air will expand during the reflow process and may/will

cause the device to twist/move.

• The antenna pin (pin 5) has an impedance of ~50 ohm. The antenna trace should be kept to 50 ohm to

avoid signal reflection and loss of performance. Minor deviations can be compensated by matching the

LC filter. Any transmission line calculator can be used to find the needed trace width given a board build

up. Ex: A trace width of 75 mil (1.9 mm) gives 50 impedance on a FR4 board (dielectric cons=4.4) with

copper thickness of 35µm and height (layer 1-layer 2 spacing) of 1.00 mm.

• RF circuitry is sensitive to voltage supply and therefore caution should be taken when choosing power

circuitry. To avoid “pickup” from other circuitry on the VDD lines, it is recommended to route the VDD in a

star configuration with decoupling at each circuitry and at the common connection point (see above

layout). If there are noisy circuitry in the design, it is strongly recommended to use a separate power

supply and/or place low value resistors (10ohms), inductors in series with the power supply line into these

circuitry.

• It is recommended to connect the PLL loop filter to VDD (C1, C3 and R1). The VDD connection should be

placed as close to pin 31 (VCOVDD) as possible. The MICRF505 has a integrated VCO where the

resonator circuit (varactor ) has a reference to VDD. With a common reference point, the MICRF505

(PLL) will somewhat compensate for noise present on the VDD.

• PLL loop filter components C1, C2, C3, R1 and R2 should have a compact layout and should be placed

as close to pin 27 and 29. Avoid signal traces/bus and noisy circuitry around/close/under this area.

• Digital high speed logic or noisy circuitry should/must be at a safe distance from RF circuitry or RF VDD

as this might/will cause degradation of sensitivity and create spurious emissions. Example of such

circuitry is LCD display, charge pumps, RS232, clock / data bus etc.

Micrel MICRF505BML/YML

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Package Information MICRF505LBML

MICRF505BML

32-Pin MLF (B)

Micrel MICRF505BML/YML

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Package Information MICRF505YML

D D2 E E2 e b L CPL H h H2 Units

5.0 3.10±0.10 5.0 3.10±0.10 0.5 0.25 0.4±0.05 0.20 0.85±0.05 0.00~0.05 0.2 mm

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Overview of programming bit

Address Data

A6..A0 D7 D6 D5 D4 D3 D2 D1 D0

0000000 LNA_by PA2 PA1 PA0 Sync_en Mode1 Mode0 Load_en

0000001 Modulation1 Modulation0

OL_opamp_en

(“0”) PA_LDc_en

(”0”) RSSI_en LD_en PF_FC1 PF_FC0

0000010 CP_HI SC_by

VCO_by

(“0”) PA_by OUTS3 OUTS2 OUTS1 OUTS0

0000011 IFBias_s

(“1”) IFA_HG

(“1”) VCO_BIAS_s

(“0”) VCO_IB2 VCO_IB1 VCO_IB0 VCO_freq1 VCO_freq0

0000100 Mod_F2 Mod_F1 Mod_F0 Mod_I4 Mod_I3 Mod_I2 Mod_I1 Mod_I0

0000101 - -

Mod_FHG

(“0”) Mod_shape

(“1”) Mod_A3 Mod_A2 Mod_A1 Mod_A0

0000110 - Mod_clkS2 Mod_clkS1 Mod_clkS0 BitSync_clkS2 BitSync_clkS1 BitSync_clkS0 BitRate_clkS2

0000111 BitRate_clkS1 BitRate_clkS0 RefClk_K5 RefClk_K4 RefClk_K3 RefClk_K2 RefClk_K1 RefClk_K0

0001000 SC_HI

(“1”) ScClk_X2

(“1”) ScClk5 ScClk4 ScClk3 ScClk2 ScClk1 ScClk0

0001001 PrescalMode_s

(“0”) Prescal_s

(“0”) XCOAR_en

(”1”) XCOtune4 XCOtune3 XCOtune2 XCOtune1 XCOtune0

0001010 - - A0_5 A0_4 A0_3 A0_2 A0_1 A0_0

0001011 - - - - N0_11 N0_10 N0_9 N0_8

0001100 N0_7 N0_6 N0_5 N0_4 N0_3 N0_2 N0_1 N0_0

0001101 - - - - M0_11 M0_10 M0_9 M0_8

0001110 M0_7 M0_6 M0_5 M0_4 M0_3 M0_2 M0_1 M0_0

0001111 - - A1_5 A1_4 A1_3 A1_2 A1_1 A1_0

0010000 - - - - N1_11 N1_10 N1_9 N1_8

0010001 N1_7 N1_6 N1_5 N1_4 N1_3 N1_2 N1_1 N1_0

0010010 - - - - M1_11 M1_10 M1_9 M1_8

0010011 M1_7 M1_6 M1_5 M1_4 M1_3 M1_2 M1_1 M1_0

0010100 Div2_HI

(“1”) LO_IB1

(“0”) LO_IB0

(“1”) PA_IB4

(”1”) PA_IB3

(”0”) PA_IB2

(”1”) PA_IB1

(”0”) PA_IB0

(“1”)

0010101 - - - - FEEC_3 FEEC_2 FEEC_1 FEEC_0

0010110 FEE_7 FEE_6 FEE_5 FEE_4 FEE_3 FEE_2 FEE_1 FEE_0

Table 1: Detailed description of programming bit

ADR # BIT # NAME DESCRIPTI ON COMMENTS

0000000 7 By_LNA LNA bypass on/off

6 PA2 Power amplifier level, 3.bit Ref. Table 6

5 PA1 Power amplifier level, 2.bit Ref. Table 6

4 PA0 Power amplifier level, 1.bit Ref. Table 6

3 Sync_en Synchronizer Mode bit Ref. Table 3

2 Mode1 Main Mode selection 2. Bit Ref. Table 2

1 Mode0 Main Mode selection 1. Bit Ref. Table 2

0 Load_en Load generation (1=enable)

0000001 7 Modulation1 Modulation selection 2.bit Ref. Table 4

6 Modulation0 Modulation selection 1.bit Ref. Table 4

5 OL_opamp_en “0” mandatory. Opamp in OpenLoop circuit (0=disable)

4 PA_LDc_en

“0” mandatory. PA controlled by Lock Detect

(0=disable) Ref. Table 6

3 RSSI_en RSSI function (1=enable)

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2 LD_en Lock detect function (1=enable)

1 PF_FC1 Prefilter corner frequency 2.bit Ref. Table 5

0 PF_FC0 Prefilter corner frequency 1.bit Ref. Table 5

0000010 7 CP_HI High charge-pump current (0=125uA, 1=500uA)

6 SC_by Bypass of Switched Capacitor filter (1=enable)

5 VCO_by “0” mandatory. Bypass of VCO (1=enable)

4 PA_by Bypass of PA (1=enable)

3 OUTS3 Test pins output 4.bit Ref. Table 8

2 OUTS2 Test pins output 3.bit Ref. Table 8

1 OUTS1 Test pins output 2.bit Ref. Table 8

0 OUTS0 Test pins output 1.bit Ref. Table 8

0000011 7 IFBias_s “1” mandatory.

6 IFA_HG “1” mandatory. High gain setting in preamplifier

5 VCO_Bias_s

“0” mandatory. Select separate bias for VCO on

VCOBias pin (1=enable)

4 VCO_IB2 VCO bias current setting, 3. bit (111 = highest current)

3 VCO_IB1 VCO bias current setting, 2. bit

2 VCO_IB0 VCO bias current setting, 1. bit

1 VCO_freq1 Frequency setting of VCO, 2. bit (11=highest frequency)

0 VCO_freq0 Frequency setting of VCO, 1.bit

0000100 7 Mod_F2 Modulator filter setting, MSB (0=filter active)

6 Mod_F1 Modulator filter setting

5 Mod_F0 Modulator filter setting, LSB

4 Mod_I4 Modulator current setting, MSB

3 Mod_I3 Modulator current setting

2 Mod_I2 Modulator current setting

1 Mod_I1 Modulator current setting

0 Mod_I0 Modulator current setting, LSB

0000101 7 --------- Reserved/not in use

6 --------- Reserved/not in use

5 Mod_FHG “0” mandatory. Modulator Test bit.

4 Mod_shape “1” mandatory. Modulator shape enable

3 Mod_A3 Modulator attenuator setting, MSB (1=attenuator active)

2 Mod_A2 Modulator attenuator setting

1 Mod_A1 Modulator attenuator setting

0 Mod_A0 Modulator attenuator setting, LSB

0000110 7 --------- Reserved/not in use

6 Mod_clkS2 Modulator clock setting 3.bit, MSB

5 Mod_clkS1 Modulator clock setting 2.bit

4 Mod_clkS0 Modulator clock setting 1.bit, LSB

3 BitSync_clkS2 BitSync clock setting 3.bit, MSB

2 BitSync_clkS1 BitSync clock setting 2.bit

1 BitSync_clkS0 BitSync clock setting 1.bit, LSB

0 BitRate_clkS2 Bitrate clock setting 3.bit, MSB

0000111 7 BitRate_clkS1 Bitrate clock setting 2.bit

6 BitRate_clkS0 Bitrate clock setting 1.bit. LSB:

5 RefClk_K5 Reference clock divider 6.bit, MSB

4 RefClk_K4 Reference clock divider 5.bit

3 RefClk_K3 Reference clock divider 4.bit

2 RefClk_K2 Reference clock divider 3.bit

1 RefClk_K1 Reference clock divider 2.bit

0 RefClk_K0 Reference clock divider 1.bit, LSB

0001000 7 SC_HI “1” mandatory. High current in Switched Cap filter

6 ScClk_X2 “1” mandatory. Switched Cap clock multiplied by two

5 ScClk5 SwitchCap clock divider 6.bit MSB

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4 ScClk4 SwitchCap clock divider 5.bit

3 ScClk3 SwitchCap clock divider 4.bit

2 ScClk2 SwitchCap clock divider 3.bit

1 ScClk1 SwitchCap clock divider 2.bit

0 ScClk0 SwitchCap clock divider 1.bit, LSB

0001001 7 PrescalMode_s

“0” mandatory. Selects A, N and M divider output

control of prescaler mode

6 Prescal_s “0” mandatory. Selects pulse swallow prescaler.

5 XCOAR_en “1” mandatory. Set XCO amplitude regulation on.

4 XCOtune4 Crystal oscillator trimming, LSB

3 XCOtune3 Crystal oscillator trimming

2 XCOtune2 Crystal oscillator trimming

1 XCOtune1 Crystal oscillator trimming

0 XCOtune0 Crystal oscillator trimming, MSB

0001010 7 --------- Reserved/not in use

6 --------- Reserved/not in use

5 A0_5 A0-counter 6.bit

4 A0_4 A0-counter 5.bit

3 A0_3 A0-counter 4.bit

2 A0_2 A0-counter 3.bit

1 A0_1 A0-counter 2.bit

0 A0_0 A0-counter 1.bit

0001011 7 --------- Reserved/not in use

6 --------- Reserved/not in use

5 --------- Reserved/not in use

4 --------- Reserved/not in use

3 N0_11 N0-counter 12.bit

2 N0_10 N0-counter 11.bit

1 N0_9 N0-counter 10.bit

0 N0_8 N0-counter 9.bit

0001100 7 N0_7 N0-counter 8.bit

6 N0_6 N0-counter 7.bit

5 N0_5 N0-counter 6.bit

4 N0_4 N0-counter 5.bit

3 N0_3 N0-counter 4.bit

2 N0_2 N0-counter 3.bit

1 N0_1 N0-counter 2.bit

0 N0_0 N0-counter 1.bit

0001101 7 --------- Reserved/not in use

6 --------- Reserved/not in use

5 --------- Reserved/not in use

4 --------- Reserved/not in use

3 M0_11 M0-counter 12.bit

2 M0_10 M0-counter 11.bit

1 M0_9 M0-counter 10.bit

0 M0_8 M0-counter 9.bit

0001110 7 M0_7 M0-counter 8.bit

6 M0_6 M0-counter 7.bit

5 M0_5 M0-counter 6.bit

4 M0_4 M0-counter 5.bit

3 M0_3 M0-counter 4.bit

2 M0_2 M0-counter 3.bit

1 M0_1 M0-counter 2.bit

0 M0_0 M0-counter 1.bit

0001111 7 --------- Reserved/not in use

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6 --------- Reserved/not in use

5 A1_5 A1-counter 6.bit

4 A1_4 A1-counter 5.bit

3 A1_3 A1-counter 4.bit

2 A1_2 A1-counter 3.bit

1 A1_1 A1-counter 2.bit

0 A1_0 A1-counter 1.bit

0010000 7 --------- Reserved/not in use

6 --------- Reserved/not in use

5 --------- Reserved/not in use

4 --------- Reserved/not in use

3 N1_11 N1-counter 12.bit

2 N1_10 N1-counter 11.bit

1 N1_9 N1-counter 10.bit

0 N1_8 N1-counter 9.bit

0010001 7 N1_7 N1-counter 8.bit

6 N1_6 N1-counter 7.bit

5 N1_5 N1-counter 6.bit

4 N1_4 N1-counter 5.bit

3 N1_3 N1-counter 4.bit

2 N1_2 N1-counter 3.bit

1 N1_1 N1-counter 2.bit

0 N1_0 N1-counter 1.bit

0010010 7 --------- Reserved/not in use

6 --------- Reserved/not in use

5 --------- Reserved/not in use

4 --------- Reserved/not in use

3 M1_11 M1-counter 12.bit

2 M1_10 M1-counter 11.bit

1 M1_9 M1-counter 10.bit

0 M1_8 M1-counter 9.bit

0010011 7 M1_7 M1-counter 8.bit

6 M1_6 M1-counter 7.bit

5 M1_5 M1-counter 6.bit

4 M1_4 M1-counter 5.bit

3 M1_3 M1-counter 4.bit

2 M1_2 M1-counter 3.bit

1 M1_1 M1-counter 2.bit

0 M1_0 M1-counter 1.bit

0010100 7 Div2_HI “1” mandatory. Sets high bias current in Div2 circuit

6 LO_IB1 “0” mandatory. Bias current setting of LObuffer, MSB

5 LO_IB0 “1” mandatory. Bias current setting of LObuffer, LSB

4 PA_IB4 “0” mandatory. Bias current setting of PA,MSB

3 PA_IB3 “0” mandatory. Bias current setting of PA

2 PA_IB2 “0” mandatory. Bias current setting of PAbuffer, MSB Ref. Table 9

1 PA_IB1 “1” mandatory. Bias current setting of PAbuffer Ref. Table 9

0 PA_IB0 “1” mandatory. Bias current setting of PAbuffer, LSB Ref. Table 9

0010101 7 --------- Reserved/not in use

6 --------- Reserved/not in use

5 --------- Reserved/not in use

4 --------- Reserved/not in use

3 FEEC_3 FEE control bit Ref. Table 11

2 FEEC_2 FEE control bit Ref. Table 11

1 FEEC_1 FEE control bit Ref. Table 10

0 FEEC_0 FEE control bit Ref. Table 10

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0010110 7 FEE_7 FEE value, bit 7, MSB

6 FEE_6 FEE value, bit 6

5 FEE_5 FEE value, bit 5

4 FEE_4 FEE value, bit 4

3 FEE_3 FEE value, bit 3

2 FEE_2 FEE value, bit 2

1 FEE_1 FEE value, bit 1

0 FEE_0 FEE value, bit 0, LSB

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Table 2: Main Mode bit

Mode1 Mode0 State Comments

0 0 Power down Keeps Register configuration

0 1 Standby Crystal Oscillator running

1 0 Receive Full Receive

1 1 Transmit Full Transmit ex. PA stage

Table 3: Synchronizer mode bit

Sync_en State Comments

0 Rx: Bit synchronization off Transparent reception of data

0 Tx: DataClk pin off Transparent transmission of data

1 Rx: Bit synchronization on Bit-clock is generated by transceiver

1 Tx: DataClk pin on. Bit-clock is generated by transceiver

Table 4: Modulation bit

Modulation1 Modulation0 State Comments

0 0

Closed loop VCO-modulation VCO is phase-locked

0 1

Open loop VCO-modulation Not recommend

1 0

Modulation by A,M and N Modulation inside PLL

1 1

Not defined Reserved for future use

Table 5: Prefilter bit

PF_FC1 PF_FC0 State

0 0 3 dB filter corner at 100 KHz

0 1 3 dB filter corner at 150 KHz

1 0 3 dB filter corner at 230 KHz

1 1 3 dB filter corner at 340 KHz

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Table 6: Power amplifier bit

PA2 PA1 PA0

State

0 0 0

21dB attenuation/PA off

0 0 1

18dB attenuation

0 1 0

15dB attenuation

0 1 1

12dB attenuation

1 0 0

9dB attenuation

1 0 1

6dB attenuation

1 1 0

3dB attenuation

1 1 1

Max output

PALDc_en

0 PA is turned off by PA2=PA1=PA0=0

1 PA is turned on/off by Lock Detect, LD=1 -> PA on

PA2=PA1=PA0=0 now gives 21dB attenuation

PA_By

0 Power Amplifier enabled

1 Power Amplifier bypassed, approx 20dB reduced output power.

Table 7:Generation of Bitrate_clk, BitSync_clk and Mod_clk.

BitRate_clk

BitSync_clk

Mod_clk

Clock frequency

(F is crystal frequency, K

is RefClk integer)

S2 S1 S0

0 0 0 F/(64K)

0 0 1 F/(32K)

0 1 0 F/(16K)

0 1 1 F/(8K)

1 0 0 F/(4K)

1 0 1 F/(2K)

1 1 0 F/K (*)

1 1 1 F (*)

(*) Can not be used as BitRate_clk.

Table 8: Test signals

OutS3 OutS2 OutS1 OutS0 IchOut QchOut Ichout2 / RSSI QchOut2 / NC

0 0 0 0 Gnd Gnd Gnd Gnd

0 0 0 1 Ip mixer In mixer Ip IFamp In IFamp

0 0 1 0 Qp mixer Qn mixer Qp IFamp Qn IFamp

0 0 1 1 Ip IFamp In IFamp Ip SC-filter In SC-filter

0 1 0 0 Qp IFamp Qn IFamp Qp SC-filter Qn SC-filter

0 1 0 1 Ip SC-filter In SC-filter Gnd I limiter

0 1 1 0 Qp SC-filter Qn SC-filter Gnd Q limiter

0 1 1 1 Ip mixer In mixer Ip SC-filter In SC-filter

1 0 0 0 Qp mixer Qn mixer Qp SC-filter Qn SC-filter

1 0 0 1 Ip mixer In mixer Gnd I limiter

1 0 1 0 Qp mixer Qn mixer Gnd Q limiter

1 0 1 1 Ip mixer Qp mixer ModIn PrescalMode

1 1 0 0 Ip IFamp Qp IFamp TI1 TQ1

1 1 0 1 Ip SC-filter Qp SC-filter DemodUp DemodDn

1 1 1 0 I limiter Q limiter Demod MAout

1 1 1 1 N-div M-div Phi1n Phi2n

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Table 9: PAbuffer bias current setting

PA_IB2 PA_IB1 PA_IB0 State

0 0 0

PAbuffer uses bias current from PTATBias source, external resistor (Pin 2)

0 0 1

PAbuffer uses bias current from separate bias source, external resistor (Pin 8)

0 1 0

PAbuffer uses bias current from internal bias source, lowest current

0 1 1

PAbuffer uses bias current from internal bias source

1 0 0

PAbuffer uses bias current from internal bias source, typical current

1 0 1

PAbuffer uses bias current from internal bias source

1 1 0

PAbuffer uses bias current from internal bias source

1 1 1

PAbuffer uses bias current from internal bias source, highest current

Table 10: Frequency Error Estimation control bit

FEEC_1 FEEC_0 FEE Mode

0 0 Off

0 1 Counting UP pulses

1 0 Counting DN pulses

1 1

Counting UP and DN pulses. UP increments the

counter, DN decrements it.

Table 11: Frequency Error Estimation control bit, cont.

FEEC_3 FEEC_2 No. of DEMOD_DT bit used during the

measurement.

0 0 8

0 1 16

1 0 32

1 1 64

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TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com

The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel

for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a

product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended

for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a

significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a

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