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參數(shù)資料
| 型號(hào)： | CY2281 |
| 廠商： | Cypress Semiconductor Corp. |
| 英文描述： | 100-MHz PentiumII Clock Synthesizer/Driver with Spread Spectrum for Mobile or Desktop PCs(應(yīng)用于移動(dòng)或桌上型PC機(jī)并帶有寬頻譜的100MHz奔騰II時(shí)鐘合成器/驅(qū)動(dòng)器) |
| 中文描述： | 100兆赫PentiumII時(shí)鐘合成器/驅(qū)動(dòng)器，帶有擴(kuò)頻移動(dòng)或桌面電腦（應(yīng)用于移動(dòng)或桌上型電腦機(jī)并帶有寬頻譜的100MHz的奔騰二時(shí)鐘合成器/驅(qū)動(dòng)器譜） |
| 文件頁(yè)數(shù)： | 1/9頁(yè) |
| 文件大?。?/td> | 121K |
| 代理商： | CY2281 |
PRELIMINARY
100MHz Pentium
II Clock Synthesizer/Driver
with Spread Spectrum for Mobile PCs
CY2281
Cypress Semiconductor Corporation
3901 North First Street
San Jose
CA 95134
408-943-2600
July 21, 1999
Features
Mixed 2.5V and 3.3V operation
Complete clock solution for Pentium II, and other sim-
ilar processor-based motherboards
—Two CPU clocks at 2.5V up to 100 MHz
—Six synchronous PCI clocks, one free-running
—One 3.3V Ref. clock at 14.318 MHz
—One 3.3V USB clock at 48 MHz (-2S only)
Spread Spectrum clocking for EMI control (-11S, -2S)
1.5–4.0 ns delay between CPU and PCI clocks
Power-down, CPU stop and PCI stop pins
Low skew outputs,
≤
175 ps between CPU clocks
Factory-EPROM programmable output drive and slew
rate for EMI customization
Available in space-saving 28-pin SSOP package
Functional Description
The CY2281 is a clock synthesizer/driver for Pentium II, or
other similar processor-based mobile PCs requiring up to 100
MHz support. The CY2281 outputs two CPU clocks at 2.5V.
There are six PCI clocks, running at one-half or one-third the
CPU clock frequency of 66.6 MHz and 100 MHz respectively.
One of the PCI clocks is free-running. Additionally, the part
outputs one 3.3V reference clock at 14.318 MHz. The
CY2281-2S also provides one 3.3V USB clock at 48 MHz.
The CY2281-11S and CY2281-2S incorporate the Intel-de-
fined spread spectrum feature. They provide a –0.6%
downspread on the CPU and PCI clocks, which can help re-
duce EMI in certain high-speed systems. A summary of clock
outputs for both devices is shown below.
The part possesses power-down, CPU stop, and PCI stop pins
for power management control. The signals are synchronized
on-chip, and ensure glitch-free transitions on the outputs.
When the CPU_STOP input is asserted, the CPU clock out-
puts are driven LOW. When the PCI_STOP input is asserted,
the PCI clock outputs (except the free-running PCI clock) are
driven LOW. When the PWR_DWN pin is asserted, the refer-
ence oscillator and PLLs are shut down, and all outputs are
driven LOW.
The CY2281 clock outputs are designed for low EMI emis-
sions. Controlled rise and fall times, unique output driver cir-
cuits, and innovative circuit layout techniques enable the
CY2281 to have lower EMI than clock devices from other man-
ufacturers. Additionally, factory-EPROM programmable output
drive and slew-rate control enable optimal configurations.
CY2281 Selector Guide
Note:
1.
One free-running PCI clock.
Clock Outputs
-1
-11S
-2S
CPU (66, 100 MHz)
2
2
2
PCI (CPU/2, CPU/3)
6
[1]
6
[1]
6
[1]
REF (14.318 MHz)
1
1
1
USB (48 MHz)
N/A
N/A
1
CPU-PCI delay
1.5–4.0 ns
1.5–4.0 ns
1.5–4.0 ns
Spread Spectrum
None
–0.6%
–0.6%
Intel and Pentium are registered trademarks of Intel Corporation.
Pin Configuration
Logic Block Diagram
EPROM
XTALOUT
XTALIN
14.318
MHz
OSC.
CPU
PLL
SEL100
Delay
REF
CPUCLK [0–1]
V
DDCPU
PCI [1-5]
PCICLK_F
STOP
LOGIC
STOP
LOGIC
SEL
CPU_STOP
PWR_DWN
Divider
PCI_STOP
V
DDPCI
V
DDPCI
V
DDREF
1
2
3
4
5
6
7
8
9
10
11
12
13
14
16
15
19
18
17
28-Pin SSOP
Top View
28
27
26
25
24
23
20
21
22
C
XTALIN
XTALOUT
PCICLK_F
V
SS
PCICLK1
V
DDPCI
PCICLK2
PCICLK3
V
DDPCI
PCICLK4
PCICLK5
V
SS
V
SS
V
SS
V
DDREF
REF
V
DDCPU
CPUCLK0
CPUCLK1
V
SS
AV
DD
V
SS
PCI_STOP
CPU_STOP
PWR_DWN
SEE CHART BELOW
SEL100
V
DDUSB
Option
-1,-11S
-2S
Pin 16
SEL
USBCLK
USBCLK (-2S only)
V
DDUSB
SYS
PLL
(-1/-11S only)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| CY2282-1 | 100-MHz PentiumII Clock Synthesizer/Driver with Spread Spectrum and USB for Desktop PCs(應(yīng)用于桌上型PC機(jī)并帶有擴(kuò)展頻譜和USB的100MHz奔騰II時(shí)鐘合成器/驅(qū)動(dòng)器) |
| CY2282-11S | 100-MHz PentiumII Clock Synthesizer/Driver with Spread Spectrum and USB for Desktop PCs(應(yīng)用于桌上型PC機(jī)并帶有擴(kuò)展頻譜和USB的100MHz奔騰II時(shí)鐘合成器/驅(qū)動(dòng)器) |
| CY2283 | PentiumII, K6, 6x86 100-MHz Clock Synthesizer/Driver for Desktop PCs with ALI or VIA Chipsets, AGP and 3 DIMMs(帶ALI或VIA芯片組，AGP和3DIMM應(yīng)用于桌上型PC機(jī)的奔II，K6, 6x86 100MHz時(shí)鐘合成器/驅(qū)動(dòng)器) |
| CY2285 | 100-MHz PentiumII Clock Synthesizer/Driver with Spread Spectrum for Mobile PCs(應(yīng)用于移動(dòng)PC機(jī)并帶有寬頻譜的100MHz奔騰II時(shí)鐘合成器/驅(qū)動(dòng)器) |
| CY2292FIT | Three-PLL General-Purpose EPROM Programmable Clock Generator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| CY2283 | 制造商:CYPRESS 制造商全稱:Cypress Semiconductor 功能描述:PentiumII, K6, 6x86 100-MHz Clock Synthesizer/Driver for Desktop PCs with ALI or VIA Chipsets, AGP and 3 DIMMs |
| CY2283PVC-1 | 制造商:CYPRESS 制造商全稱:Cypress Semiconductor 功能描述:PentiumII, K6, 6x86 100-MHz Clock Synthesizer/Driver for Desktop PCs with ALI or VIA Chipsets, AGP and 3 DIMMs |
| CY2283PVC-2 | 制造商:CYPRESS 制造商全稱:Cypress Semiconductor 功能描述:PentiumII, K6, 6x86 100-MHz Clock Synthesizer/Driver for Desktop PCs with ALI or VIA Chipsets, AGP and 3 DIMMs |
| CY2285 | 制造商:CYPRESS 制造商全稱:Cypress Semiconductor 功能描述:100-MHz Pentium㈢II Clock Synthesizer/Driver with Spread Spectrum for Mobile PCs |
| CY2285PVC-1 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:CPU System Clock Generator |
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