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October 2003  
rev 1.0  
ASM3P1819A-H  
Peak Reducing EMI Solution  
Features  
•
Eight Spread % Selections:  
•
FCC approved method of EMI  
o
± 0.625% to –3.5%.  
attenuation.  
•
•
3.3V operating voltage.  
•
•
Provides up to 15dB EMI reduction.  
Generates a low EMI spread spectrum  
clock and a non-spread reference clock  
of the input frequency.  
CMOS/TTL compatible inputs and  
outputs.  
•
•
Low-power CMOS design.  
Supports notebook VGA and other LCD  
timing controller applications.  
Power down function for mobile  
application.  
•
•
•
•
Optimized for frequency range from  
20MHz to 40MHz.  
•
•
•
Internal loop filter minimizes external  
components and board space.  
Selectable spread options: Down and  
Center Spread.  
Products are available for industrial  
temperature range.  
Available in 8-pin SOIC and TSSOP  
packages.  
Low inherent cycle-to-cycle jitter.  
The ASM3P1819x 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 results 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.  
Product Description  
The ASM3P1819x is  
a
versatile spread  
spectrum  
frequency  
modulator designed  
specifically for input clock frequencies from  
20MHz to 40MHz. The ASM3P1819x can  
generate an EMI reduced clock form an OSC or  
a system-generated clock. The ASM3P1819x  
offers Down and Center spread options with  
different percentage deviations. (Refer Spread  
Deviation Selections Table.)  
The ASM3P1819x uses the most efficient and  
optimized modulation profile approved by the  
FCC and is implemented by using a proprietary  
all-digital method.  
The ASM3P1819x reduces electromagnetic  
interference (EMI) at the clock source, allowing  
system wide reduction of EMI of down stream  
clock and data dependent signals. The  
ASM3P1819x allows significant system cost  
savings by reducing the number of circuit board  
layers and shielding that are traditionally  
required to pass EMI regulations.  
Applications  
The ASM3P1819x is targeted towards EMI  
management for memory and LVDS interfaces  
in mobile graphic chipsets and high-speed digital  
applications such as PC peripheral devices,  
consumer electronics, and embedded controller  
systems.  
Alliance Semiconductor  
2595, Augustine Drive • Santa Clara • CA 95054 • Tel 408 855 4900 • Fax 408 855 4999 • www.alsc.com  
Notice: The information in this document is subject to change without notice.  
Octoberr 2003  
rev 1.0  
ASM3P1819A-H  
Block Diagram  
SRS  
D_C PD#  
Modulation  
VDD  
PLL  
XIN  
Crystal  
Oscillator  
Frequency  
Divider  
Output  
Phase  
Loop  
VCO  
XOUT  
Divider  
Detector  
Filter  
Feedback  
Divider  
ModOUT  
REF  
VSS  
Pin Diagram  
XIN  
1
2
3
4
8
7
6
5
XOUT  
XIN  
VSS  
1
2
3
4
8
7
6
5
XOUT  
VSS  
VDD  
PD#  
VDD  
PD#  
SRS  
D_C  
REF  
REF  
ModOUT  
ModOUT  
ASM3P1819A-D  
Pin Name  
ASM3P1819E-H  
Pin Description  
Pin#  
Type  
Description  
ASM3P1819A-D  
ASM3P1819E-H  
1
2
XIN  
VSS  
XIN  
VSS  
I
P
Connect to externally generated clock signal or crystal.  
Ground to entire chip.  
Digital logic input used to select Down (LOW) or Center  
(HIGH) spread options (Refer Spread Deviation  
Selection Table.) This pin has an internal pull-up  
resistor.  
3
D_C  
I
Spread range select. Digital logic input used to select  
frequency deviation (Refer Spread Deviation Selection  
Table.)  
3
SRS  
I
4
5
ModOUT  
REF  
ModOUT  
REF  
O
O
Spread spectrum clock output.  
Un-modulated reference output clock of the input  
frequency.  
Power-Down control pin. Pull LOW to enable Power-  
Down mode. This pin has an internal pull-up resistor.  
6
7
8
PD#  
VDD  
PD#  
REF  
I
P
O
Connect to +3.3V.  
Crystal connection. If connected to an externally  
XOUT  
XOUT  
generated clock, this pin must be left unconnected.  
Low EMI Clock for Mobile VGA  
2 of 8  
Notice: The information in this document is subject to change without notice.  
Octoberr 2003  
rev 1.0  
ASM3P1819A-H  
Input Frequency and Modulation Rate  
Input Frequency Range  
Output Frequency Range  
(MHz)  
Part Number  
Modulation Rate  
(MHz)  
ASM3P1819A-H  
20 to 40  
20 to 40  
Input frequency / 512  
Spread Deviation Selections  
Part Number  
SRS  
D-C  
Spread Deviation  
- 2.5% (Down)  
0
1
0
1
0
1
0
1
ASM3P1819A  
N/A  
-3.50% (Down)  
- 1.25% (Down)  
-1.75% (Down)  
±1.25% (Center)  
± 1.75% (Center)  
±0.625% (Center)  
±0.875 % (Center)  
- 1.25% (Down)  
± 0.625% (Center)  
- 2.5% (Down)  
ASM3P1819B  
ASM3P1819C  
ASM3P1819D  
ASM3P1819E  
ASM3P1819F  
ASM3P1819G  
ASM3P1819H  
N/A  
N/A  
N/A  
0
1
0
1
0
1
0
1
N/A  
N/A  
N/A  
N/A  
± 1.25% (Center)  
- 1.75% (Down)  
± 0.875% (Center)  
- 3.5% (Down)  
±3.50% (Center)  
Absolute Maximum Ratings  
Symbol  
VDD, VIN  
TSTG  
Parameter  
Rating  
Unit  
V
°C  
°C  
Voltage on any pin with respect to GND  
Storage temperature  
-0.5 to + 7.0  
-65 to +125  
0 to 70  
TA  
Operating temperature  
Note: These are stress ratings only and functional operation is not implied. Exposure to absolute  
maximum ratings for extended periods may affect device reliability.  
Low EMI Clock for Mobile VGA  
3 of 8  
Notice: The information in this document is subject to change without notice.  
Octoberr 2003  
rev 1.0  
ASM3P1819A-H  
DC Electrical Characteristics  
Unless otherwise noted, VDD = 3.3V and TA =25°C  
Symbol  
VIL  
Parameter  
Min  
GND – 0.3  
Typ  
Max  
0.8  
VDD + 0.3  
-20.0  
1.00  
12.00  
12.00  
0.4  
Unit  
V
V
µA  
µA  
mA  
mA  
V
Input low voltage  
Input high voltage  
-
-
-
-
-
-
-
-
VIH  
IIL  
IIH  
IXOL  
IXOH  
VOL  
VOH  
2.00  
-60.0  
-
2.00  
-
Input low current (inputs D_C, PD#)  
Input high current  
XOUT output low current (@ 0.4V, VDD = 3.3V)  
XOUT output high current (@2.5V, VDD = 3.3V)  
Output low voltage (VDD = 3.3V, IOL = 20mA)  
Output high voltage (VDD = 3.3V, IOH = 20mA)  
-
2.8  
-
V
Dynamic supply current normal mode (3.3V and  
ICC  
7.1 fIN - min  
-
26.9 fIN - max  
mA  
10pF loading)  
IDD  
VDD  
Static supply current standby mode  
Operating voltage  
Power up time (first locked clock cycle after power  
-
-
4.5  
3.3  
-
-
mA  
V
tON  
-
-
0.18  
50  
-
-
mS  
up)  
ZOUT  
Clock output impedance  
Ω
AC Electrical Characteristics  
Symbol  
fIN  
fOUT  
tLH*  
tHL*  
tJC  
Parameter  
Input frequency  
Output frequency  
Output rise time (measured at 0.8V to 2.0V)  
Output fall time (measured at 2.0V to 0.8V)  
Jitter (cycle to cycle)  
Min  
20  
20  
-
Typ Max Unit  
-
-
40  
40  
-
MHz  
MHz  
ns  
ns  
ps  
0.69  
0.66  
-
-
-
-200  
45  
200  
55  
tD  
Output duty cycle  
50  
%
* tLH and tHL are measured into a capacitive load of 15pF  
Low EMI Clock for Mobile VGA  
4 of 8  
Notice: The information in this document is subject to change without notice.  
Octoberr 2003  
rev 1.0  
ASM3P1819A-H  
Package Information  
8-Pin SOIC  
H
E
D
A2  
A
C
θ
e
A1  
D
L
B
Symbol  
Dimensions in inches  
Dimensions in millimeters  
Min  
Max  
Min  
1.35  
0.10  
1.35  
0.33  
0.33  
4.78  
3.80  
Max  
1.75  
0.25  
1.75  
0.53  
0.53  
5.00  
4.01  
A
A1  
A2  
B
0.053  
0.004  
0.053  
0.013  
0.007  
0.188  
0.150  
0.069  
0.010  
0.069  
0.022  
0.012  
0.197  
0.158  
C
D
E
e
0.050 BSC  
1.27 BSC  
H
L
0.228  
0.016  
0°  
0.244  
0.035  
8°  
5.80  
0.40  
0°  
6.20  
0.89  
8°  
θ
Low EMI Clock for Mobile VGA  
5 of 8  
Notice: The information in this document is subject to change without notice.  
Octoberr 2003  
rev 1.0  
ASM3P1819A-H  
8-Pin TSSOP  
H
E
D
A2  
A
C
θ
e
A1  
L
B
Dimensions in inches  
Dimensions in millimeters  
Symbol  
Min  
Max  
Min  
Max  
1.10  
0.15  
0.95  
0.30  
0.20  
3.10  
4.50  
A
A1  
A2  
B
0.043  
0.006  
0.037  
0.012  
0.008  
0.122  
0.177  
0.002  
0.033  
0.008  
0.004  
0.114  
0.169  
0.05  
0.85  
0.19  
0.09  
2.90  
4.30  
C
D
E
e
0.026 BSC  
0.65 BSC  
H
L
0.244  
0.020  
0°  
0.260  
0.028  
8°  
6.20  
0.50  
0°  
6.60  
0.70  
8°  
θ
Low EMI Clock for Mobile VGA  
6 of 8  
Notice: The information in this document is subject to change without notice.  
Octoberr 2003  
rev 1.0  
ASM3P1819A-H  
Ordering Information  
Temperature Range  
Part Number  
ASM3P1819xST  
ASM3P1819xSR  
ASM3P1819xTT  
ASM3P1819xTR  
ASM3I1819xST  
ASM3I1819xSR  
ASM3I1819xTT  
ASM3I1819xTR  
Package Configuration  
8-Pin SOIC  
Tube  
Tape and Reel  
Tube  
Commercial  
Commercial  
Commercial  
Commercial  
Industrial  
8-Pin SOIC  
8-Pin TSSOP  
8-Pin TSSOP  
8-Pin SOIC  
Tape and Reel  
Tube  
8-Pin SOIC  
Tape and Reel  
Tube  
Industrial  
8-Pin TSSOP  
8-Pin TSSOP  
Industrial  
Tape and Reel  
Industrial  
Device Ordering Information  
OR - SOT23/T/R  
SR - SOIC, T/R  
QR – QFN, T/R  
QT - QFN, TUBE  
BT - BGA, TUBE  
BR – BGA, T/R  
TT – TSSOP, TUBE  
TR - TSSOP, T/R  
VT – TVSOP, TUBE  
VR – TVSOP, T/R  
ST – SOIC, TUBE  
A S M 3 P 1 8 1 9 x S T  
X = A/B/C/D/E/F/G/H  
PART NUMBER  
X = Automotive  
I = Industrial  
P or n/c = Commercial  
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  
Alliance Semiconductor Mixed Signal Product  
Licensed under US patent numbers 5,488,627 and 5,631,920.  
Low EMI Clock for Mobile VGA  
7 of 8  
Notice: The information in this document is subject to change without notice.  
Octoberr 2003  
rev 1.0  
ASM3P1819A-H  
Alliance Semiconductor Corporation  
2595, Augustine Drive,  
Santa Clara, CA 95054  
Tel# 408-855-4900  
Copyright © Alliance Semiconductor  
All Rights Reserved  
Part Number: ASM3P1819A-H  
Document Version: v1.0  
Fax: 408-855-4999  
www.alsc.com  
© 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, and is not intended to  
operate as, or provide, any guarantee or warrantee to any user or customer. Alliance 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 Alliance 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 Alliance's Terms and  
Conditions of Sale (which are available from Alliance). All sales of Alliance products are made exclusively according to  
Alliance's Terms and Conditions of Sale. The purchase of products from Alliance does not convey a license under any patent  
rights, copyrights; mask works rights, trademarks, or any other intellectual property rights of Alliance or third parties. Alliance  
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 Alliance products in such life-supporting  
systems implies that the manufacturer assumes all risk of such use and agrees to indemnify Alliance against all claims arising  
from such use.  
Low EMI Clock for Mobile VGA  
8 of 8  
Notice: The information in this document is subject to change without notice.