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February 2007  
rev 1.4  
ASM3P2531A  
Low Frequency EMI Reduction  
Features  
dependent signals. It allows significant system cost  
savings by reducing the number of circuit board layers  
and shielding traditionally required to pass EMI  
regulations.  
•
FCC approved method of EMI attenuation.  
•
Generates a low EMI spread spectrum of the  
input clock frequency.  
•
•
Optimized for input frequency range between  
27MHz – 55MHz.  
Internal loop filter minimizes external  
components and board space.  
The ASM3P2531A modulates the output of a single PLL  
in order to spread the bandwidth of a synthesized clock,  
thereby decreasing the peak amplitudes of its harmonics.  
This result in significantly lower system EMI compared to  
the typical narrow band signal produced by oscillators  
and most clock generators. Lowering EMI by increasing  
a signal’s bandwidth is called spread spectrum clock  
generation.  
•
•
•
•
•
Frequency Deviation: ±1.7%.  
Low inherent Cycle-to-cycle jitter.  
3.3 V ± 0.3V Operating Voltage.  
Ultra low power CMOS design:3.0 mA @ 3.3 V.  
Supports notebook VGA and other LCD timing  
controller applications.  
The ASM3P2531A uses the most efficient and optimized  
modulation profile approved by the FCC and is  
implemented by using a proprietary all-digital method.  
•
Available in 8-pin SOIC and TSSOP Packages.  
Product Description  
Applications  
The ASM3P2531A is  
a versatile spread spectrum  
frequency modulator designed specifically for a wide  
range of clock frequencies. It reduces electromagnetic  
interference (EMI) at the clock source allowing system-  
wide reduction of EMI of downstream clock and data  
The ASM3P2531A is targeted toward the notebook VGA  
chip and other displays using an LVDS interface, PC  
peripheral devices, and embedded systems.  
Block Diagram  
VDD  
STOP  
PLL  
Modulation  
CLKIN  
Crystal  
Frequency  
Divider  
Oscillator  
Output  
Divider  
Phase  
Loop  
Filter  
VCO  
Detector  
Feedback  
Divider  
ModOUT  
VSS  
PulseCore Semiconductor Corporation  
1715 S. Bascom Ave Suite 200, Campbell, CA 95008 • Tel: 408-879-9077 • Fax: 408-879-9018  
www.pulsecoresemi.com  
Notice: The information in this document is subject to change without notice.  
February 2007  
ASM3P2531A  
rev 1.4  
Pin Configuration (8-pin SOIC and TSSOP Packages)  
NC  
NC  
8
7
CLKIN  
VDD  
1
2
ASM3P2531A  
NC  
6
5
VSS  
3
4
STOP  
ModOUT  
Spread Range Selection, VDD = 3.3 V  
CLKIN frequency  
Spreading range  
Modulation rate  
27MHz – 55MHz  
± 1.7%  
(CLKIN/1280) KHz  
Pin Description  
Pin# Pin Name Type  
Description  
1
2
3
4
CLKIN  
VDD  
I
External reference frequency input.  
Power supply for the entire chip.  
Ground to entire chip.  
P
P
O
VSS  
ModOUT  
Spread spectrum clock output or reference output.( Refer Standby Mode Selection.)  
5
STOP  
I
Active LOW signal. When HIGH, enables ModOUT and when LOW, ModOUT would be  
LOW.  
6
7
8
NC  
NC  
NC  
-
-
-
No connect.  
No connect.  
No connect.  
Low Frequency EMI Reduction  
2 of 8  
Notice: The information in this document is subject to change without notice.  
February 2007  
ASM3P2531A  
rev 1.4  
Schematic for a Typical Application  
Input clock 27MHz – 55MHz  
VDD  
CLKIN  
VDD  
NC  
NC  
1
2
8
7
6
5
FB  
FB : Optional ferrite bead  
ASM3P2531A  
0.1uF  
NC  
3
4
VSS  
VDD  
0 ꢀ  
0 ꢀ  
GND  
ModOUT  
STOP  
EMI reduced clock output  
27MHz – 55MHz  
Use either pull-up or pull-down  
resistors with 0Ω  
Absolute Maximum Ratings  
Symbol  
VDD, VIN  
Parameter  
Voltage on any pin with respect to Ground  
Rating  
-0.5 to +4.6  
Unit  
V
TSTG  
TA  
Ts  
Storage temperature  
Operating temperature  
Max. Soldering Temperature (10 sec)  
Junction Temperature  
-65 to +125  
-40 to +85  
260  
°C  
°C  
°C  
°C  
TJ  
150  
Static Discharge Voltage  
(As per JEDEC STD22- A114-B)  
TDV  
2
KV  
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.  
Low Frequency EMI Reduction  
3 of 8  
Notice: The information in this document is subject to change without notice.  
February 2007  
ASM3P2531A  
rev 1.4  
DC Electrical Characteristics  
Symbol  
Parameter  
Min  
VSS - 0.3  
2.0  
Typ  
Max  
0.8  
VDD + 0.3  
-35  
Unit  
V
V
µA  
µA  
V
VIL  
VIH  
IIL  
Input low voltage  
Input high voltage  
Input low current  
Input high current  
Output low voltage  
Output high voltage  
IIH  
35  
0.4  
VOL  
VOH  
IDD  
VDD = 3.3V, IOL = 6 mA  
VDD = 3.3V, IOH = 15 mA  
Static supply current standby mode  
2.5  
V
3.0  
mA  
mA  
V
mS  
ꢀ
ICC  
Dynamic supply current  
3.3V and 15pF loading  
10  
3.0  
14  
3.6  
VDD  
tON  
ZOUT  
Operating voltage  
3.3  
0.18  
50  
Power-up time (first locked cycle after power up)  
Clock output impedance  
AC Electrical Characteristics  
Symbol  
Parameter  
Min  
27  
27  
0.4  
0.4  
Typ  
Max  
55  
55  
1.2  
1.2  
360  
55  
Unit  
MHz  
MHz  
nS  
nS  
pS  
fIN  
fOUT  
tLH  
tHL  
Input frequency  
Output frequency  
Output rise time  
Output fall time  
1
Measured from 0.8 V to 2.0 V  
Measured from 2.0 V to 0.8 V  
0.6  
0.6  
1
tJC  
TD  
Jitter (Cycle to cycle)  
Output duty cycle  
45  
50  
%
Note 1: tLH and tHL are measured into a capacitive load of 15pF  
Low Frequency EMI Reduction  
4 of 8  
Notice: The information in this document is subject to change without notice.  
February 2007  
rev 1.4  
ASM3P2531A  
Package Information  
8-lead (150-mil) SOIC Package  
H
E
D
A2  
A
C
θ
e
A1  
L
B
Dimensions  
Symbol  
Inches  
Millimeters  
Min  
Max  
0.010  
0.069  
0.059  
0.020  
0.010  
Min  
0.10  
1.35  
1.25  
0.31  
0.18  
Max  
0.25  
1.75  
1.50  
0.51  
0.25  
A1  
A
0.004  
0.053  
0.049  
0.012  
0.007  
A2  
B
C
D
E
0.193 BSC  
0.154 BSC  
0.050 BSC  
0.236 BSC  
4.90 BSC  
3.91 BSC  
1.27 BSC  
6.00 BSC  
e
H
L
0.016  
0°  
0.050  
8°  
0.41  
0°  
1.27  
8°  
θ
Low Frequency EMI Reduction  
5 of 8  
Notice: The information in this document is subject to change without notice.  
February 2007  
rev 1.4  
ASM3P2531A  
8-lead Thin Shrunk Small Outline Package (4.40-MM Body)  
H
E
D
A2  
A
C
θ
e
A1  
L
B
Dimensions  
Symbol  
Inches  
Millimeters  
Min  
Max  
Min  
Max  
A
A1  
A2  
B
0.043  
0.006  
0.037  
0.012  
0.008  
0.122  
0.177  
1.10  
0.002  
0.033  
0.008  
0.004  
0.114  
0.169  
0.05  
0.85  
0.19  
0.09  
2.90  
4.30  
0.15  
0.95  
0.30  
0.20  
3.10  
4.50  
c
D
E
e
0.026 BSC  
0.252 BSC  
0.65 BSC  
6.40 BSC  
H
L
0.020  
0°  
0.028  
8°  
0.50  
0°  
0.70  
8°  
θ
Low Frequency EMI Reduction  
6 of 8  
Notice: The information in this document is subject to change without notice.  
February 2007  
rev 1.4  
ASM3P2531A  
Ordering Information  
Ordering Code  
Marking  
Package Type  
8-pin 150mil SOIC –TUBE, Pb free  
8-pin 150-mil SOIC -TAPE & REEL, Pb free  
8-pin 150mil SOIC -TUBE, Pb free  
8-pin 150-mil SOIC -TAPE & REEL, Pb free  
8-pin 4.4mm TSSOP -TUBE, Pb free  
8-pin 4.4mm TSSOP -TAPE & REEL, Pb free  
8-pin 4.4mm TSSOP -TUBE, Pb free  
8-pin 4.4mm TSSOP - TAPE & REEL, Pb free  
8-pin 150mil SOIC –TUBE, Green  
Operating Range  
Commercial  
Commercial  
Industrial  
3P2531AF  
ASM3P2531AF-08ST  
ASM3P2531AF-08SR  
ASM3I2531AF-08ST  
ASM3I2531AF-08SR  
ASM3P2531AF-08TT  
ASM3P2531AF-08TR  
ASM3I2531AF-08TT  
ASM3I2531AF-08TR  
ASM3P2531AG-08ST  
ASM3P2531AG-08SR  
ASM3I2531AG-08ST  
ASM3I2531AG-08SR  
ASM3P2531AG-08TT  
ASM3P2531AG-08TR  
ASM3I2531AG-08TT  
ASM3I2531AG-08TR  
3P2531AF  
3P2531AF  
3P2531AF  
3P2531AF  
3P2531AF  
3P2531AF  
3P2531AF  
3P2531AG  
3P2531AG  
3P2531AG  
3P2531AG  
3P2531AG  
3P2531AG  
3P2531AG  
3P2531AG  
Industrial  
Commercial  
Commercial  
Industrial  
Industrial  
Commercial  
Commercial  
Industrial  
8-pin 150-mil SOIC -TAPE & REEL, Green  
8-pin 150mil SOIC -TUBE, Green  
8-pin 150-mil SOIC -TAPE & REEL, Green  
8-pin 4.4mm TSSOP -TUBE, Green  
8-pin 4.4mm TSSOP -TAPE & REEL, Green  
8-pin 4.4mm TSSOP -TUBE, Green  
8-pin 4.4mm TSSOP - TAPE & REEL, Green  
Industrial  
Commercial  
Commercial  
Industrial  
Industrial  
Device Ordering Information  
A S M 3 P 2 5 3 1 A F - 0 8 T R  
R = Tape & Reel, T = Tube or Tray  
O = SOT  
U = MSOP  
E = TQFP  
L = LQFP  
U = MSOP  
P = PDIP  
S = SOIC  
T = TSSOP  
A = SSOP  
V = TVSOP  
B = BGA  
D = QSOP  
X = SC-70  
Q = QFN  
DEVICE PIN COUNT  
F = LEAD FREE AND RoHS COMPLIANT PART  
G = GREEN PACKAGE, LEAD FREE, and RoHS  
DEVICE NUMBER  
X= Automotive  
I= Industrial  
P or n/c = Commercial  
(0C to +70C)  
(-40C to +125C) (-40C to +85C)  
1 = Reserved  
6 = Power Management  
7 = Power Management  
8 = Power Management  
9 = Hi Performance  
0 = Reserved  
2 = Non PLL based  
3 = EMI Reduction  
4 = DDR support products  
5 = STD Zero Delay Buffer  
PulseCore Semiconductor Mixed Signal Product  
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920.  
Low Frequency EMI Reduction  
7 of 8  
Notice: The information in this document is subject to change without notice.  
February 2007  
rev 1.4  
ASM3P2531A  
Copyright © PulseCore Semiconductor  
All Rights Reserved  
PulseCore Semiconductor Corporation  
1715 S. Bascom Ave Suite 200  
Campbell, CA 95008  
Part Number: ASM3P2531A  
Document Version: v1.4  
Tel: 408-879-9077  
Fax: 408-879-9018  
www.pulsecoresemi.com  
Note: This product utilizes US Patent # 6,646,463 Impedance Emulator Patent issued to PulseCore Semiconductor, dated 11-11-2003  
© Copyright 2007 PulseCore Semiconductor Corporation. All rights reserved. Our logo and name are trademarks or  
registered trademarks of PulseCore Semiconductor. All other brand and product names may be the trademarks of their  
respective companies. PulseCore reserves the right to make changes to this document and its products at any time without  
notice. PulseCore assumes no responsibility for any errors that may appear in this document. The data contained herein  
represents PulseCore’s best data and/or estimates at the time of issuance. PulseCore 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, and is not intended to operate as, or provide, any guarantee or warrantee to any user or  
customer. PulseCore does not assume any responsibility or liability arising out of the application or use of any product  
described herein, and disclaims any express or implied warranties related to the sale and/or use of PulseCore products  
including liability or warranties related to fitness for a particular purpose, merchantability, or infringement of any intellectual  
property rights, except as express agreed to in PulseCore’s Terms and Conditions of Sale (which are available from  
PulseCore). All sales of PulseCore products are made exclusively according to PulseCore’s Terms and Conditions of Sale.  
The purchase of products from PulseCore does not convey a license under any patent rights, copyrights; mask works rights,  
trademarks, or any other intellectual property rights of PulseCore or third parties. PulseCore does not authorize its products  
for use as critical components in life-supporting systems where a malfunction or failure may reasonably be expected to result  
in significant injury to the user, and the inclusion of PulseCore products in such life-supporting systems implies that the  
manufacturer assumes all risk of such use and agrees to indemnify PulseCore against all claims arising from such use.  
Low Frequency EMI Reduction  
8 of 8  
Notice: The information in this document is subject to change without notice.