January 2005 ASM3P2759A
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Low Power Peak EMI Reducing Solution 1 of 11
Notice: The information in this document is subject to change without notice.
Low Power Peak EMI Reducing Solution
Features
Generates an EMI optimized clock signal at the
output.
Integrated loop filter components.
Operates with a 3.3V / 2.5V Supply.
Operating current less than 4mA.
Low power CMOS design.
Input frequency range: 3MHz to 5MHz for 2.5V
:3MHz to 6MHz for 3.3V
Generates a 1X low EMI spread spectrum clock of
the input frequency.
Frequency deviation: ±1% @ 3MHz
Available in 6-pin TSOT-23, 8-pin SOIC and 8-pin
TSSOP packages.
Product Description
The ASM3P2759A is a versatile spread spectrum
frequency modulator designed specifically for a wide
range of clock frequencies. The ASM3P2759A reduces
electromagnetic interference (EMI) at the clock source,
allowing system wide reduction of EMI of all clock
dependent signals. The ASM3P2759A allows significant
system cost savings by reducing the number of circuit
board layers ferrite beads, shielding that are traditionally
required to pass EMI regulations.
The ASM3P2759A uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented by using a proprietary all digital method.
The ASM3P2759A modulates the output of a single PLL
in order to “spread” the bandwidth of a synthesized clock,
and more importantly, decreases the peak amplitudes of
its harmonics. This results in significantly lower system
EMI compared to the typical narrow band signal produced
by oscillators and most frequency generators. Lowering
EMI by increasing a signal’s bandwidth is called ‘spread
spectrum clock generation’.
Applications
The ASM3P2759A is targeted towards all portable devices
with very low power requirements like MP3 players and
digital still cameras.
Key Specifications
Description Specification
Supply voltages VDD = 3.3V / 2.5V
Cycle-to-Cycle Jitter 200 pS (Max)
Output Duty Cycle 45/55% (worst case)
Modulation Rate Equation FIN/128
Frequency Deviation ±1% @ 3MHz
Block Diagram
ModOUT
VDD
XIN
VSS
Frequency
Divider
Feedback
Divider
Modulation
Phase
Detector
Loop
Filter
VCO Output
Divider
PLL
PD
Crystal
Oscillator
XOUT
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Notice: The information in this document is subject to change without notice.
Pin Configuration (6-pin TSOT- 23 Package)
Pin# Pin Name Type Description
1 I Power-down control pin. Pull low to enable power-down mode. Connect to VDD if not
used.
2XOUT O Crystal connection. If using an external reference, this pin must be left unconnected.
3XIN/CLKIN I
Crystal connection or external reference frequency input. This pin has dual functions. It
can be connected either to an external crystal or an external reference clock.
4VDD P Power supply for the entire chip
5ModOUT O Spread spectrum clock output.
6VSS P Ground connection.
PD
XOUT
1
2
34
5
6
ASM3P2759A
PD
XIN/CLKIN VDD
ModOUT
VSS
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Notice: The information in this document is subject to change without notice.
XIN/CLKIN
VSS
ModOUT
NC
Pin Configuration (8-pin SOIC and TSSOP Package)
Pin Description
Pin# Pin Name Type Description
1XIN/CLKIN I
Crystal connection or external reference frequency input. This pin has dual functions. It
can be connected either to an external crystal or an external reference clock.
2XOUT O Crystal connection. If using an external reference, this pin must be left unconnected.
3 I Power-down control pin. Pull low to enable power-down mode. Connect to VDD if not
used.
4NC – No connect.
5VSS P Ground connection.
6ModOUT O Spread spectrum clock output.
7NC – No connect.
8VDD P Power supply for the entire chip
Modulation Profile
Specification
Description Specification
For 2.5V Supply 3MHz < CLKIN < 5MHz
Frequency Range For 3.3V Supply 3MHz < CLKIN < 6MHz
Modulation Equation FIN/128
Frequency Deviation ±1% @ 3MHz
PD
XOUT
1
2
3
45
6
7
8
ASM3P2759A
PD
NC
VDD
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Low Power Peak EMI Reducing Solution 4 of 11
Notice: The information in this document is subject to change without notice.
Absolute Maximum Ratings
Symbol Parameter Rating Unit
VDD, VIN Voltage on any pin with respect to Ground 0.5 to +7.0 V
TSTG Storage temperature -65 to +125 °C
TAOperating temperature 0to 70 °C
TsMax. Soldering Temperature (10 sec) 260 °C
TJJunction Temperature 150 °C
TDV Static Discharge Voltage
(As per MIL-STD-883, Method 3015)
2KV
Note: These are stress ratings only and are not implied for functional use. Exposure to absolute maximum ratings for prolonged periods of time may affect
device reliability.
DC Electrical Characteristics for 2.5V Supply
(Test condition: All parameters are measured at room temperature (+25°C) unless otherwise stated)
Symbol Parameter Min Typ Max Unit
VIL Input low voltage GND - 0.3 – 0.8 V
VIH Input high voltage 2.0 – VDD + 0.3 V
IIL Input low current – – -35 NA
IIH Input high current – – 35 NA
IXOL XOUT output low current (@0.5V, VDD=2.5V) – 3 – mA
IXOH XOUT output high current (@1.8V, VDD=2.5V) – 3 – mA
VOL Output low voltage (VDD = 2.5 V, IOL = 8 mA) – –
0.6
V
VOH Output high voltage (VDD = 2.5 V, IOH = 8 mA) 1.8 – – V
IDD Static supply current* – – 10 uA
ICC Dynamic supply current (2.5V, 3MHz and with no load) – 2.0 – mA
VDD Operating voltage 2.375 2.5 2.625 V
tON Power-up time (first locked cycle after power-up)** – – 5 mS
ZOUT Output impedance – 50 – Q
*XIN/CLKIN and PD pin are pulled low
** VDD and XIN/CLKIN input are stable, PD pin is made high from low.
AC Electrical Characteristics for 2.5V Supply
Symbol Parameter Min Typ Max Unit
CLKIN Input frequency 3 – 5 MHz
ModOUT Output frequency 3 – 5 MHz
Input Frequency = 3MHz – – ±1
fdFrequency Deviation Input Frequency = 5MHz – – ±0.58 %
tLH*Output rise time (measured from 0.7V to 1.7V) 0.5 1.0 1.2 nS
tHL*Output fall time (measured from 1.7V to 0.7V) 0.4 0.9 1.1 nS
tJC Jitter (cycle to cycle) – – 200 pS
tDOutput duty cycle 45 50 55 %
* tLH and tHL are measured into a capacitive load of 15pF
January 2005 ASM3P2759A
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Low Power Peak EMI Reducing Solution 5 of 11
Notice: The information in this document is subject to change without notice.
DC Electrical Characteristics for 3.3V Supply
(Test condition: All parameters are measured at room temperature (+ 25°C) unless otherwise stated)
Symbol Parameter Min Typ Max Unit
VIL Input low voltage GND -
0.3 –0.8 V
VIH Input high voltage 2.0 – VDD + 0.3 V
IIL Input low current – – -35 NA
IIH Input high current – – 35 NA
IXOL XOUT output low current (@0.4V, VDD=3.3V) – 3 – mA
IXOH XOUT output high current (@2.5V, VDD=3.3V) – 3 – mA
VOL Output low voltage (VDD = 3.3 V, IOL = 8 mA) – – 0.4 V
VOH Output high voltage (VDD = 3.3 V, IOH = 8 mA) 2.5 – – V
IDD Static supply current* – 10 uA
ICC Dynamic supply current (3.3V, 3MHz and with no load) – 2.5 – mA
VDD Operating voltage 2.7 3.3 3.6 V
tON Power-up time (first locked cycle after power-up)** – – 5 mS
ZOUT Output impedance – 45 – Q
*XIN/CLKIN and PD pin are pulled low
** VDD and XIN/CLKIN input are stable; PD pin is made high from low.
AC Electrical Characteristics for 3.3V Supply
Symbol Parameter Min Typ Max Unit
CLKIN Input frequency 3 – 6 MHz
ModOUT Output frequency 3 – 6 MHz
Input Frequency = 3MHz – – ±1
fdFrequency
Deviation Input Frequency = 6MHz – – ±0.56
%
tLH*Output rise time (measured from 0.8 to 2.0V) 0.4 1.0 1.2 nS
tHL *Output fall time (measured at 2.0V to 0.8V) 0.4 0.9 1.0 nS
tJC Jitter (cycle to cycle) – – 200 pS
tDOutput duty cycle 45 50 55 %
*tLH and tHL are measured into a capacitive load of 15pF
January 2005 ASM3P2759A
rev 1.5
Low Power Peak EMI Reducing Solution 6 of 11
Notice: The information in this document is subject to change without notice.
Typical Crystal Oscillator Circuit
Typical Crystal Specifications
Fundamental AT cut parallel resonant crystal
Nominal frequency 4.800 MHz
Frequency tolerance ± 50 ppm or better at 25°C
Operating temperature range -25°C to +85°C
Storage temperature -40°C to +85°C
Load capacitance 18pF
Shunt capacitance 7pF maximum
ESR 25
R1 = 510Q
C1 = 27 pF C2 = 27 pF
Crystal
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Notice: The information in this document is subject to change without notice.
Package Information
6-pin TSOT-23 Package
Dimensions
Inches Millimeters
Symbol
Min Max Min Max
A0.04 1.00
A1 0.00 0.004 0.00 0.10
A2 0.033 0.036 0.84 0.90
b0.012 0.02 0.30 0.50
H0.005 BSC 0.127 BSC
D0.114 BSC 2.90 BSC
B0.06 BSC 1.60 BSC
e0.0374 BSC 0.950 BSC
C0.11 BSC 2.80 BSC
L0.0118 0.02 0.30 0.50
T0° 4° 0° 4°
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Low Power Peak EMI Reducing Solution 8 of 11
Notice: The information in this document is subject to change without notice.
8-Pin SOIC Package
D
EH
D
A1
A2
A
L
C
B
e
Dimensions
Inches Millimeters
Symbol
Min Max Min Max
A1 0.004 0.010 0.10 0.25
A0.053 0.069 1.35 1.75
A2 0.049 0.059 1.25 1.50
B0.012 0.020 0.31 0.51
C0.007 0.010 0.18 0.25
D0.193 BSC 4.90 BSC
E0.154 BSC 3.91 BSC
e0.050 BSC 1.27 BSC
H0.236 BSC 6.00 BSC
L0.016 0.050 0.41 1.27
T0° 8° 0° 8°
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Low Power Peak EMI Reducing Solution 9 of 11
Notice: The information in this document is subject to change without notice.
E
H
A
A1
A2
D
B
C
L
e
8-Pin TSSOP Package
Dimensions
Inches Millimeters
Symbol
Min Max Min Max
A0.043 1.10
A1 0.002 0.006 0.05 0.15
A2 0.033 0.037 0.85 0.95
B0.008 0.012 0.19 0.30
c0.004 0.008 0.09 0.20
D0.114 0.122 2.90 3.10
E0.169 0.177 4.30 4.50
e0.026 BSC 0.65 BSC
H0.252 BSC 6.40 BSC
L0.020 0.028 0.50 0.70
T0° 8° 0° 8°
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Low Power Peak EMI Reducing Solution 10 of 11
Notice: The information in this document is subject to change without notice.
Ordering Information
Part Number Marking Package Type Temperature
ASM3P2759AF-06OR O4LL 6-Pin TSOT-23, TAPE & REEL 0°C – 70°C
ASM3P2759AF-08TT ASM3P2759AFT 8-Pin TSSOP, TUBE 0°C – 70°C
ASM3P2759AF-08TR ASM3P2759AFT 8-Pin TSSOP, TAPE & REEL 0°C – 70°C
ASM3P2759AF-08ST ASM3P2759AFS 8-Pin SOIC, TUBE 0°C – 70°C
ASM3P2759AF-08SR ASM3P2759AFS 8-Pin SOIC, TAPE & REEL 0°C – 70°C
ASM3P2759A-06OR O1LL 6-Pin TSOT-23, TAPE & REEL 0°C – 70°C
ASM3P2759A-08TT ASM3P2759AT 8-Pin TSSOP, TUBE 0°C – 70°C
ASM3P2759A-08TR ASM3P2759AT 8-Pin TSSOP, TAPE & REEL 0°C – 70°C
ASM3P2759A-08ST ASM3P2759AS 8-Pin SOIC, TUBE 0°C – 70°C
ASM3P2759A-08SR ASM3P2759AS 8-Pin SOIC, TAPE & REEL 0°C – 70°C
Device Ordering Information
ASM3P2759AF-08TR
Licensed under U.S Patent Nos 5,488,627 and 5,631,921
OR - TSOT23-6,T/R SR - SOIC, T/R
TT – TSSOP, TUBE QR – QFN, T/R
TR - TSSOP, T/R QT - QFN, TUBE
VT – TVSOP, TUBE BT - BGA, TUBE
VR – TVSOP, T/R BR – BGA, T/R
ST – SOIC, TUBE
PIN COUNT
X = Automotive I = Industrial P or n/c = Commercial
(-40C to +125C) (-40C to +85C) (0C to +70C)
1 – reserved 6 – power management
2 - Non PLL based 7 – power management
3–EMI Reduction 8 – power management
4–DDR support products 9 – Hi performance
5
–
STD Zero Delay Buffer
0
-
reserved
Alliance Semiconductor Mixed Signal Product
PART NUMBER
LEAD FREE PART
January 2005 ASM3P2759A
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Low Power Peak EMI Reducing Solution 11 of 11
Notice: The information in this document is subject to change without notice.
Note: This product utilizes US Patent # 6,646,463 Impedance Emulator Patent issued to Alliance Semiconductor, dated 11-11-2003
©Copyright 2003 Alliance Semiconductor Corporation. All rights reserved. Our three-point logo, our name and Intelliwatt are
trademarks or registered trademarks of Alliance. All other brand and product names may be the trademarks of their respective
companies. Alliance reserves the right to make changes to this document and its products at any time without notice. Alliance
assumes no responsibility for any errors that may appear in this document. The data contained herein represents Alliance's
best data and/or estimates at the time of issuance. Alliance reserves the right to change or correct this data at any time,
without notice. If the product described herein is under development, significant changes to these specifications are possible.
The information in this product data sheet is intended to be general descriptive information for potential customers and users,
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Preliminary Information
Part Number: ASM3P2759A
Document Version: v1.5
