PASM3P2821B-08TT [ALSC]
Clock Generator;
| 型号： | PASM3P2821B-08TT |
| 厂家： | 
ALLIANCE SEMICONDUCTOR CORPORATION |
| 描述： | Clock Generator |
| 文件： | 总7页 (文件大小：174K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
October 2003
rev 1.0
ASM3P2821B
The ASM3P2821B reduces electromagnetic interference
(EMI) at the clock source, allowing system wide reduction
of EMI of down stream clock and data dependent
signals. The ASM3P2821B 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.
Features
ꢀ
ꢀ
FCC approved method of EMI attenuation.
Generates a 1X low EMI spread spectrum clock of
the input frequency.
ꢀ
ꢀ
Input frequency range: 15MHz – 27MHz.
Internal loop filter minimizes external components
and board space.
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Frequency deviation: -2.5%
The ASM3P2821B 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.
TTL or CMOS compatible inputs and outputs.
Ultra-low power CMOS design.
The ASM3P2821B 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’.
o
TBD mA @ 3.3V, 24MHz
ꢀ
Pinout compatible with Cypress CY25811.
Products are available for industrial temperature
range.
ꢀ
Available in 8-pin SOIC and TSSOP.
Product Description
The ASM3P2821B is
a versatile spread spectrum
frequency modulator designed specifically for input clock
frequencies in the range of 15MHz - 27MHz. The
ASM3P2821B can generate an EMI reduced clock from a
ceramic resonator or system clock. The ASM3P2821B
offers a percentage deviation of –2.5%.
Applications
The ASM3P2821B is targeted towards EMI management
for high speed digital applications such as PC peripheral
devices, consumer electronics and embedded controller
systems.
VDD
Block Diagram
PLL
Modulation
XIN
Crystal
Oscillator
Frequency
Divider
Output
Divider
Phase
Detector
Loop
Filter
VCO
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.
ASM3P2821B
Pin Configuration
1
2
3
4
NC
VDD
NC
8
7
6
5
XIN
VSS
NC
ASM3P2821B
ModOUT
NC
Pin Description
Pin#
Pin Name
XIN
Type
Description
1
2
3
4
5
6
7
8
I
External reference clock input.
Ground to entire chip.
No Connect.
VSS
P
NC
NC
No Connect.
MODOUT
NC
O
P
Spread spectrum low EMI output.
No Connect.
VDD
NC
Power supply for the entire chip (3.3V).
No Connect.
Low Power EMI Reduction IC
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Notice: The information in this document is subject to change without notice.
ASM3P2821B
Absolute Maximum Ratings
Symbol
Parameter
Rating
-0.5 to + 7.0
-65 to +125
0 to 70
Unit
V
VDD, VIN
TSTG
TA
Voltage on any pin with respect to GND
Storage temperature
°C
°C
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
TBD
-
-
TBD
V
V
VIH
IIL
VDD + 0.3
TBD
TBD
TBD
TBD
TBD
TBD
3.3
µA
µA
V
IIH
VOL
VOH
ICC
Output low voltage (VDD = 3.3V, IOL = 4mA)
Output high voltage (VDD = 3.3V, IOH = 4mA)
V
Dynamic supply current normal mode (3.3V and 10pF
loading)
mA
µA
V
IDD
Static supply current standby mode
Operating voltage
VDD
tON
ZOUT
TBD
TBD
Power up time (first locked clock cycle after power up)
Clock out impedance
-
-
TBD
TBD
-
-
mS
Ω
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Notice: The information in this document is subject to change without notice.
ASM3P2821B
AC Electrical Characteristics
Symbol
Parameter
Min Typ Max Unit
XIN
Input frequency
15
15
24
24
27
27
MHz
MHz
ns
MODOUT
Output frequency
tLH*
tHL*
tJC
Output rise time (measured at 0.8V to 2.0V)
Output fall time (measured at 2.0V to 0.8V)
Jitter (cycle to cycle)
TBD
TBD
-
ns
-
-
TBD
-
ps
tD
Output duty cycle
TBD
%
* 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.
ASM3P2821B
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.
ASM3P2821B
8-Pin TSSOP
H
E
D
A2
A
C
θ
e
A1
L
B
Dimensions
in millimeters
Dimensions
in inches
Symbol
Min
Max
Min
Max
1.10
0.15
1.05
0.30
0.20
3.10
4.50
A
A1
A2
`B
C
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
D
E
e
0.026 BSC
0.65 BSC
H
0.244
0.018
0°
0.260
0.030
8°
6.20
0.45
0°
6.60
0.75
8°
L
θ
Low Power EMI Reduction IC
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Notice: The information in this document is subject to change without notice.
ASM3P2821B
Alliance Semiconductor Corporation
2595, Augustine Drive,
Santa Clara, CA 95054
Tel# 408-855-4900
Copyright © Alliance Semiconductor
All Rights Reserved
Preliminary Information
Part Number: ASM3P2821B
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
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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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