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参数资料
| 型号： | CY2254A |
| 厂商： | Cypress Semiconductor Corp. |
| 英文描述： | Pentium Processor Compatible Clock Synthesizer/Driver(奔腾处理器兼容的时钟合成器/驱动器) |
| 中文描述： | 奔腾处理器兼容的时钟合成器/驱动器（奔腾处理器兼容的时钟合成器/驱动器） |
| 文件页数： | 1/6页 |
| 文件大小： | 86K |
| 代理商： | CY2254A |
Pentium Processor Compatible
Clock Synthesizer/Driver
Freq. stability = 0.01% (max.)
Output duty cycle 45% min. to 55% max.
Test mode support (
1 option only)
3.3V or 5.0V operation
Internal pull-up resistors on S0, S1, and OE inputs
CY2254A
Cypress Semiconductor Corporation
3901 North First Street
San Jose
CA 95134
408-943-2600
February 1996 - Revised June 12, 1997
Features
Multiple clock outputs to meet requirements of most
Pentium motherboards
—Four pin-selectable CPU clocks @ 66.66 MHz, 60.0
MHz, and 50.0 MHz for support of Intel Triton PCIset
based PC
—55.0 MHz pin-selectable CPU clock also available (
2
option only)
—Six PCI clocks at 1/2 CPU Clock frequency
—One I/O clock @ 24 MHz
—One Keyboard Controller clock @ 12 MHz (
1 option)
or one Universal Serial Bus clock @ 48 MHz
(
2 option)
—Two Ref. clocks @ 14.318 MHz
—Ref. 14.318 MHz Xtal oscillator input
CPU clock jitter < 200 ps cycle-to-cycle
Low skew outputs
—< 250 ps between CPU clocks
—< 250 ps between PCI clocks
—< 500 ps between CPU and PCI clocks (
2 option)
—CPU clock leads PCI clock by +1 ns min. to +4 ns
max. (
1 option)
Functional Description
The CY2254A is a Clock Synthesizer/Driver that provides the
multiple clocks required for a Pentium based PC. The
CY2254A has low-skew outputs (< 250 ps between the CPU
Clocks, < 250 ps between the PCI Clocks). In addition, the
CY2254A CPU clock outputs have less than 200 ps cy-
cle-to-cycle jitter. Finally, both the PCI and CPU clock outputs
meet the 1V/ns slew rate requirement of a Pentium proces-
sor-based system.
The CY2254A accepts a 14.318 MHz reference signal as its
input. The CY2254A has 2 PLLs, one of which generates the
CPU and PCI clocks, and the other generates the I/O and Key-
board Controller or USB clocks. The CY2254A runs off either
a 3.3V or 5V supply.
The CY2254A is available in two options. The
1 option sup-
ports the Intel Triton PCIset and provides a 12 MHz keyboard
clock on pin 25. The
2 option provides a 48 MHz USB clock
on pin 25 and supports the Cyrix M1 processor.
Intel is a registered trademark of Intel Corporation.
Pentium and Triton are trademarks of Intel Corporation.
Cyrix is a registered trademark of Cyrix Corporation.
Pin Configuration
Top View
SOIC
2254–1
Logic Block Diagram
XTALOUT
XTALIN
REF0 (14.318 MHz)
14.318
MHz
OSC.
1
2
3
4
5
6
7
8
9
10
11
12
15
16
17
18
19
20
24
23
22
21
13
14
25
28
27
26
V
DD
XTALIN
XTALOUT
V
SS
OE
CPUCLK0
CPUCLK1
V
DD
CPUCLK2
CPUCLK3
V
SS
S1
S0
V
DD
REF0
REF1
V
DD
SEE BELOW
IOCLK
V
SS
PCICLK2
PCICLK3
V
DD
PCICLK4
PCICLK5
V
SS
PCICLK1
PCICLK0
REF1 (14.318 MHz)
IOCLK (24 MHz)
CPUCLK0
CPUCLK1
CPUCLK2
CPUCLK3
PCICLK0
SYS
PLL
CPU
PLL
ROM
S0
S1
OE
÷
2
DELAY
PCICLK1
PCICLK2
PCICLK3
PCICLK4
PCICLK5
USBCLK (48 MHz)
KBDCLK (12 MHz)
÷
2
÷
2
1
2
OPTION
PIN 25
KBDCLK
12 MHz
USBCLK
48 MHz
1 option only
相关PDF资料 |
PDF描述 |
|---|---|
| CY2254 | Two-PLL Clock Generator(二锁相环时钟发生器) |
| CY2256 | Pentium and Cyrix 6x86 Compatible Clock Synthesizer/Driver for OPTi Viper Chipset(应用于 OPTi Viper芯片组的奔腾和 Cyrix公司 6x86兼容的时钟合成器/驱动器) |
| CY2273A | Pentium㈢/II, 6x86, K6 Clock Synthesizer/Driver for Desktop PCs with Intel 82430TX, 82440LX or ALI IV/IV+, AGP and 3 DIMMs |
| CY2273A-1 | Pentium㈢/II, 6x86, K6 Clock Synthesizer/Driver for Desktop PCs with Intel 82430TX, 82440LX or ALI IV/IV+, AGP and 3 DIMMs |
| CY2273A-2 | Pentium㈢/II, 6x86, K6 Clock Synthesizer/Driver for Desktop PCs with Intel 82430TX, 82440LX or ALI IV/IV+, AGP and 3 DIMMs |
相关代理商/技术参数 |
参数描述 |
|---|---|
| CY2254ASC-1 | 制造商:Rochester Electronics LLC 功能描述:PENTIUM COMPATIBLE CLOCK GENERATOR/DRIVER - Bulk |
| CY2254ASC-1T | 制造商:Cypress Semiconductor 功能描述:Pentium Processor Compatible 28-Pin SOIC T/R 制造商:Rochester Electronics LLC 功能描述:PENTIUM COMPATIBLE CLOCK GENERATOR/DRIVER - Tape and Reel |
| CY2254ASC-2 | 制造商:Cypress Semiconductor 功能描述:Pentium Processor Compatible 28-Pin SOIC |
| CY2255 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:CPU System Clock Generator |
| CY225670SNC | 制造商:Cypress Semiconductor 功能描述: |
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