BT-STA2425 - STMicroelectronics - Datasheet.Directory

December 2007 Rev 1 1/13

BT-STA2425

Bluetooth® technology module

Features

!Bluetooth® specification V 2.0 compliant

!Transmission rate up to 721 kbit/s (basic rate)

and beyond (EDR)

!Output power level: class 2 (0 dBm typical) and

class 1.5 (> 4 dBm)

!Power class 1 compatible (with external power

amplifier)

!ACL and SCO links

!Full Bluetooth® upper-layer stack including

profiles

!Supports USB1.1, UART, I2C, PCM, SPI, and

15 GPIOs

!Embedded ARM7TDMI® core processor

!Integrated 4-Mbit flash, 64-KByte RAM,

4-Kbyte ROM

!2.8-V single power supply

!Designed for low power consumption in

standby condition

!13-MHz and 32.768-kHz digital clock outputs

!No external components needed - excluding

antenna

!Module size: 29 mm x 17 mm

!Fully programmable solution

!Free development framework (CFWLite,

including real-time operating system)

!Reference designs at no additional cost

!Proved for FCC/CE and BQB compliant

designs

!Firmware library supporting profiles:

– A2DP, AVRCP sink and source

–HFP/HS

– SPP (up to 7 simultaneous connections

– Additional profiles under development

!Seamless connection with ST audio codecs

and amplifiers (STA529, STA333BW,STA328)

Applications

!Remote speakers

!Bluetooth® plug-in for TV, portable players

!Audio cradle systems

!Wireless audio systems

!Serial port replacement

!Industrial automation

!Wireless peripherals

Description

The BT-STA2425 is a flexible low-power module

enabling Bluetooth® connectivity. It is fully

programmable and capable of running the whole

stack plus custom applications.

The ARM7® embedded microcontroller can be

either programmed by the end-user or flashed

with our selection of firmware images, thereby

turning the module in a complete solution for

wireless audio connectivity or serial port

replacement.

A full set of peripherals is also available to allow

simple interfacing with other devices in the

system.

Order code: BT-STA2425

www.st.com

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Block diagram BT-STA2425

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1 Block diagram

Figure 1. Block diagram

STLC2500

STA2416

32.768

Xtal

13 Mhz

oscillator

Balun

Supply voltage

regulator

PCM

USB

I2C

UART

GPIO

ANT

32.768 kHz 13 MHz

Ext P

1.8V

RESET

JTAG

Vdd1

(2.8v)

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BT-STA2425 Pin connections

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2 Pin connections

Figure 2. Pin connections (component side)

Table 1. Pin description

Number Name Type Description

1 (1) RX_EN O RX Enable Used in Class1 application

2 (1) PA_EN O External PA enable Used in Class1 application

3 (1) PA_V1 O External PA gain setting Used in Class1 application

4 (1) PA_V0 O External PA gain setting Used in Class1 application

5 (1) ANT_SW O Antenna switch Used in Class1 application

6 PMC_A I/O Synchronous data in/out

7 PMC_B I/O Synchronous data out/in

8 PMC_SYNC I/O Synchronous data strobe

9 PMC_CLK I/O Synchronous data clock

10 NTRST I JTAG0 pin

11 TDI I JTAG1 pin

12 TMS I JTAG2 pin

13 TCK I JTAG3 pin (must be connected to ground if not used)

14 TDO I JTAG4 pin

15 13M_CK O 13 MHz oscillator out

16 RESET I

Reset pin: a low on this pin resets the module.

An internal pull-up resistor of 100 kΩ to VDD and a

capacitor of 100 nF to GND is built into the module.

17 INT2 I External interrupt signal, internally connected to GND via

10 kΩ

BT-STA2425

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Pin connections BT-STA2425

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18 UART1_RXD I UART data input

19 UART1_TXD O UART data output

20 I2C0 I/O I2C interface data, to be connected to VDD via 10 kΩ

resistor

21 I2C1 I/O I2C interface clock, to be connected to VDD by 10 kΩ

resistor

22 USB_DN I/O USB data - (negative) (connect to GND if not used)

23 USB_DP I/O USB data + (positive) (connect to GND if not used)

24 SPI_FRM I/O SPI frame sync

25 SPI_CLK I/O SPI clock

26 SPI_TXD O SPI transmit data

27 SPI_RXD I SPI receive data (connect to GND if not used)

28 GND_S PWR High-quality signal ground

29 BOOT I

External downloading enable: when low it allows the

firmware to be downloaded into the internal flash at

power-up

30 GPIO 0 I/O General purpose input / output 0

31 GPIO 1 I/O General purpose input / output 1

32 GPIO 2 I/O General purpose input / output 2

33 GPIO 3 I/O General purpose input / output 3

34 GPIO 4 I/O General purpose input / output 4

35 GPIO 5 I/O General purpose input / output 5

36 GPIO 6 I/O General purpose input / output 6

Not to be used, internally used for STLC2500 wake-up

37 GPIO 7 I/O General purpose input / output 7

38 GPIO 8 I/O General purpose input / output 8

Not to be used, internally used for STLC2500 reset

39 GPIO 9 I/O General purpose input / output 9

40 LP_CK O 32.768 kHz digital output

41 GPIO11 I/O General purpose input / output 11

42 GPIO12 I/O General purpose input / output 12

43 GPIO13 I/O General purpose input / output 13

44 GPIO14 I/O General purpose input / output 14

45 GPIO15 I/O General purpose input / output 15

46 1V8 PWR 1.8 V internal regulator output.

Not to be used – only for test purposes

Table 1. Pin description (continued)

Number Name Type Description

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47 2V8 PWR 2.8-V internal regulator output.

Not to be used – only for test purposes

48 NC I Not connected

49 VDD PWR

2.8 V power supply

The STA2416 I/Os and STLC2500 supply pins are

connected to this pin (the STA2416 supply voltage is

internally generated)

50 GND PWR Digital ground

51 GND_RF PWR RF ground

52 BT_ANTENNA I/O RF pad to be connected to the antenna

53 GND_RF PWR RF ground

1. Leave unconnected for Class-2/1.5 operation.

Table 1. Pin description (continued)

Number Name Type Description

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Electrical specification BT-STA2425

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3 Electrical specification

3.1 Absolute maximum ratings

3.2 Operating range

3.3 DC specifications

The parameters in Ta b l e 4 are specified at VDD = 2.8 V and Tamb = 25° C, unless specified

otherwise.

Table 2. Absolute maximum ratings

Symbol Parameter Min Max Unit

VDD Module supply voltage 4 V

Vin Input voltage on any digital pin GND

- 0.3

VDD

+ 0.3 V

Tstg Storage temperature -40 +85 ° C

Tsold Soldering temperature < 10s 250 ° C

Table 3. Operating range

Symbol Parameter Conditions Min Typ Max Unit

VDD Module supply voltage -20°C < T < 70°C 2.75 2.8 2.85 V

Tstg Operating ambient

temperature -20 +70 °C

Iop Operating current. VDD = 2.8 V 40 mA

Iosb Standby current. VDD = 2.8 V, Inhibit = L 100 µA

Table 4. DC specifications

Symbol Parameter Conditions Min Typ Max Unit

VIL Low level input voltage 0.8 V

VIH High level input voltage 2 2.85 V

Vhyst Schmitt trigger hysteresis 0.4 V

VOL Low level output voltage 0.2 V

VOH High level output voltage 2.4 2.85 V

13M_CKH 13 MHz output high level 2.4 V

13M_CKL 13 MHz output low level 0.3 V

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BT-STA2425 Electrical specification

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3.4 Transmitter / receiver specifications

The parameters in Ta b l e 5 are specified at VDD = 2.8 V and Tamb = 25° C, unless specified

otherwise. RF sensitivity and output power parameters are measured on the antenna pad.

For more complete information please refer to the datasheets for STA2416 and STLC2500C

Table 5. Tx/Rx specifications

Symbol Parameter Conditions Min Typ Max Unit

RFin Input frequency range 2402 2480 MHz

RX sens Receiver sensitivity BER = 0.1% -81 dBm

RFout Output frequency range 2402 2480 MHz

TXpout Nominal output power Frequency = 2402 to 2480 MHz 3 dBm

TXout Txout spectr at - 20 dBm 930 1000 kHz

ACP Channel offset = 2 -50 dBm

ACP Channel offset = 3 -55 dBm

ACP Channel offset = 4 -57 dBm

Chs Channel space 1 MHz

∆F Initial CF tolerance -75 +75 kHz

|∆f-p1|CFD 1 slot packet 25 kHz

|∆f-p3|CFD 3 slot packet 40 kHz

|∆f-p5|CFD 5 slot packet 40 kHz

|∆f/50µs|CFD rate 20 kHz/

µs

Hop Hopping 1600 hop/s

13M_CK System clock 13 MHz

System clock precision Tamb = 25° C -10 +10 ppm

System clock stability Tamb = -20° C to 70° C -20 +20 ppm

LP_CK Low-power mode clock 32.76

8kHz

Low-power mode clock

accuracy -200 +200 ppm

Tr Transmission rate Asyncronous 1.4 Mbits

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Mechanical information BT-STA2425

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4 Mechanical information

Figure 3. Module dimensions (component side)

Figure 4. Recommended land pattern (top view)

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BT-STA2425 Applications information

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5 Applications information

The following are some suggestions to better implement the BT-STA2425 module in the final

application.

"The module is usually mounted on a motherboard, so avoid routing tracks with

switching signals below the module. The best would be to have a ground plane beneath

the module.

"Connect the power supply ground of the module with the other grounds in a star

fashion on the motherboard.

"Keep the RF ground separate from the module power supply ground - the two grounds

are already connected at one point inside the module. A possible implementation is

shown in Figure 5.

Figure 5. Ground connections

The RF pin must be connected to an antenna which could be one of those shown in Figure 6

and explained as follows.

"An antenna directly printed on the PCB

"An integrated antenna, such as:

– Antenova 30-30-A5839-01

– Murata ANCV12G44SAA127

– Pulse W3008

– Yageo CAN4311153002451K

"An external antenna connected by means a SMA connector.

Figure 6. Types of antenna for the BT-STA2425 module

RF gnd

Supply voltage gnd

Module foot print

Printed-circuit antenna Integrated antenna External antenna

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Applications information BT-STA2425

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Whichever type of antenna is chosen, the connection from the RF antenna pin,

BT_ANTENNA, must follow good RF design practice and maintain the characteristic

impedance (Z0) of 50 Ω, by careful track layout, for maximum power transfer.

Figure 7. Antenna connection

50 Ω matching depends on various factors, for instance:

"the type of board material, for example FR4

"the electrical characteristics of the board, for example the relative permittivity, εr, at

2.4 GHz

"the mechanical dimensions of the board and tracks, for example PCB thickness, track

and ground thicknesses, track width.

As an example, using a 1-mm thick FR4 board (εr = 4.3 at 2.4 GHz) with copper thickness of

41 µm, the required track width for 50-Ω strip-line is 1.9 mm (microstrip-type calculation)

Figure 8. Parameters for track matching

Tools for calculating the characteristic impedance based on the physical and mechanical

characteristics of the PCB can be easily found on the internet.

Traces with Z0 = 50 ohm

Antenna connection

RF out pin

Tracks with Z0 = 50 Ω

Antenna connection

εr (Dielectric constant)

PCB

thickness

Trace width

Reference

round

Parameter

for trace matching

Trace thickness

Track thickness

Reference ground

PCB

Track width

thickness

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BT-STA2425 Trademarks and other acknowledgements

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6 Trademarks and other acknowledgements

Bluetooth is a registered trademark of Bluetooth SIG Inc.

ARM7 and ARM7TDMI are registered trademarks of ARM Limited.

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Revision history BT-STA2425

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7 Revision history

Table 6. Document revision history

Date Revision Changes

10-Dec-2007 1 Initial release.

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BT-STA2425

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