ASM3P2185B-08ST [ALSC]
Clock Generator;
| 型号： | ASM3P2185B-08ST |
| 厂家： | 
ALLIANCE SEMICONDUCTOR CORPORATION |
| 描述： | Clock Generator |
| 文件： | 总7页 (文件大小：388K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
November 2003
rev 1.1
ASM3P2185B
EMI Reduction IC
Features
The ASM3P2185B reduces electromagnetic interference
(EMI) at the clock source, allowing system wide EMI
reduction for all the down stream clocks and data
dependent signals. The ASM3P2185B allows significant
system cost savings by reducing the number of circuit
board layers, ferrite beads, shielding, and other passive
components that are traditionally required to pass EMI
regulations.
FCC approved method of EMI attenuation.
Provides up to 15dB EMI reduction.
Generates a 1X low EMI spread spectrum clock of
the input frequency.
Input frequency range: 25MHz to 50 MHz.
Internal loop filter minimizes external components
and board space.
Down Spread and Center Spread.
2 spread frequency deviation selections: -1.25%
and ± 0.8%.
The ASM3P2185B uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all digital method.
Low inherent cycle-to-cycle jitter.
3.3V operating voltage range.
TTL or CMOS compatible inputs and outputs.
Low power CMOS design.
Supports notebook VGA and other LCD timing
controller applications.
The ASM3P2185B 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’.
Products are available for industrial temperature
range.
Available in 8-pin SOIC and TSSOP.
Product Description
The ASM3P2185B is
frequency modulator designed specifically for a wide
range of input clock frequencies from 25MHz to 50MHz.
The ASM3P2185B can generate an EMI reduced clock
from an OSC or a system generated clock.
a versatile spread spectrum
Applications
The ASM3P2185B 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.
Block Diagram
SS%
VDD
PLL
Modulation
XIN
Crystal
Frequenc
y
Oscillator
Output
Phase
Loop
Filter
VCO
XOUT
Divider
Detector
Feedback
Divider
ModOUT
VSS
Alliance Semiconductor
2575, Augustine Drive • Santa Clara, CA • Tel: 408.855.4900 • Fax: 408.855.4999 • www.alsc.com
Notice: The information in this document is subject to change without notice.
November 2003
rev 1.1
ASM3P2185B
Pin Configuration
1
2
3
4
8
7
6
5
NC
XIN
XOUT
GND
NC
ASM3P2185B
VDD
ModOUT
SS%
Pin Description
Pin#
Pin Name
Type
Description
Crystal connection or external reference frequency input. This pin has dual
functions. It can be connected to either an external crystal or an external
reference clock.
1
XIN
I
Crystal connection. Input connection for an external crystal. If using an
2
3
4
XOUT
GND
SS%
I
P
I
external reference, this pin must be left unconnected.
Ground to entire chip.
Spread range select. Digital logic input used to select frequency deviation
(Refer Spread Deviation Table). This pin has an internal pull-up resistor.
5
6
7
8
ModOUT
VDD
NC
O
P
Spread spectrum low EMI output.
Power supply for the entire chip (3.3V).
No Connect.
NC
No Connect.
Spread Deviation Selection Table
SS% (pin 4)
Spread Deviation (%)
0
1
- 1.25
± 0.8%
EMI Reduction IC
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Notice: The information in this document is subject to change without notice.
November 2003
rev 1.1
ASM3P2185B
Absolute Maximum Ratings
Symbol
Parameter
Rating
-0.5 to + 7.0
-65 to +125
0 to 70
Unit
V
°C
°C
VDD, VIN
TSTG
Voltage on any pin with respect to GND
Storage temperature
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.
DC Electrical Characteristics
Symbol
Parameter
Min
Typ
Max
Unit
VIL
Input low voltage
Input high voltage
Input low current
Input high current
GND – 0.3
-
0.8
V
V
VIH
IIL
2.0
-
VDD + 0.3
-
-
-35
35
-
µA
µA
mA
mA
V
IIH
-
-
TBD
TBD
-
IXOL
IXOH
VOL
VOH
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)
-
-
-
-
0.4
-
2.5
-
V
Dynamic supply current
Normal mode (3.3V and 10pF loading)
Static supply current
ICC
IDD
8.46
12
17.78
mA
mA
0.6
Standby mode
VDD
tON
Operating voltage
2.7
3.3
0.18
50
3.7
V
mS
Ω
Power up time (first locked clock cycle after power up)
Clock out impedance
-
-
-
-
ZOUT
EMI Reduction IC
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Notice: The information in this document is subject to change without notice.
November 2003
rev 1.1
ASM3P2185B
AC Electrical Characteristics
Symbol
Parameter
Min Typ Max Unit
XIN
ModOUT
tLH*
Input frequency
25
25
-
-
50
50
MHz
MHz
ns
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)
1.2 1.32 1.4
tHL*
0.8
-
0.9
-
1.0
360
55
ns
tJC
ps
TD
Output duty cycle
45
50
%
tLH and tHL are measured into a capacitive load of 15pF
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Notice: The information in this document is subject to change without notice.
November 2003
rev 1.1
ASM3P2185B
Package Information
8-Pin SOIC
H
E
D
A2
A
C
θ
e
A1
L
B
Symbol Dimensions in inches Dimensions in millimeters
Min
Max
0.071
0.010
0.069
0.020
0.01
Min
1.45
0.10
1.35
0.31
0.10
4.72
3.75
Max
1.80
0.25
1.75
0.51
0.25
5.12
4.15
A
A1
A2
B
0.057
0.004
0.053
0.012
0.004
0.186
0.148
C
D
0.202
0.164
E
e
0.050 BSC
1.27 BSC
H
0.224
0.012
0°
0.248
0.028
8°
5.70
0.30
0°
6.30
0.70
8°
L
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Notice: The information in this document is subject to change without notice.
November 2003
rev 1.1
ASM3P2185B
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
1.05
0.30
0.20
3.10
4.50
A
A1
A2
B
0.047
0.002
0.031
0.007
0.004
0.114
0.169
0.006
0.041
0.012
0.008
0.122
0.177
0.05
0.80
0.19
0.09
2.90
4.30
C
D
E
e
0.026 BSC
0.65 BSC
H
L
0.244
0.018
0°
0.260
0.030
8°
6.20
0.45
0°
6.60
0.75
8°
θ
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920.
EMI Reduction IC
6 of 7
Notice: The information in this document is subject to change without notice.
November 2003
rev 1.1
ASM3P2185B
Alliance Semiconductor Corporation
2575, Augustine Drive,
Santa Clara, CA 95054
Tel# 408-855-4900
Copyright © Alliance Semiconductor
All Rights Reserved
Preliminary Information
Part Number: ASM3P2185B
Document Version: v1.1
Fax: 408-855-4999
www.alsc.com
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, and is not intended to operate as, or provide, any guarantee or warrantee to any user or
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EMI Reduction IC
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Notice: The information in this document is subject to change without notice.
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