cy2275a Cypress Semiconductor Corporation., cy2275a Datasheet - Page 2

• Manufacturer Part Number: cy2275a
• Description: Pentium Clock Synthesizer/driver Desktop With Intel 82440lx With Dimms
• Manufacturer: Cypress Semiconductor Corporation.

Pin Summary
Function Table
Actual Clock Frequency Values
V
V
V
AV
V
XTALIN
XTALOUT
SDRAM7/
PCI_STOP
SDRAM6/
CPU_STOP
SDRAM5/
PWR_DWN
SDRAM[0:4],[8:11] 38, 37, 35, 34, 32,
OE
CPUCLK[0:3]
PCICLK[0:5]
PCICLK_F
IOAPIC[0:1]
REF0
SDATA
SCLK
MODE
Note:
0
1
CPUCLK
Clock Output
2.
Name
DDQ3
DDQ2
DDCPU
SS
DD
OE
For best accuracy, use a parallel-resonant crystal, C
[2]
[2]
14.318 MHz
14.318 MHz
XTALIN
66.67
Frequency
Target
(MHz)
Pins
6, 14, 19, 30, 36
48
42
1
3, 9, 16, 22, 27, 33,
39, 45
4
5
28
29
31
21, 20, 18, 17
26
44, 43, 41, 40
8, 10, 11, 12, 13, 15
7
47, 46
2
23
24
25
Hi-Z
66.67 MHz
SDRAM[0:11]
CPUCLK[0:3]
66.654
Frequency
Actual
(MHz)
3.3V Digital voltage supply
IOAPIC Digital voltage supply, 2.5V
CPU Digital voltage supply, 2.5V
Analog voltage supply, 3.3V
Ground
Reference crystal input
Reference crystal feedback
SDRAM clock output. Also, active LOW control input to stop PCI clocks, enabled
when MODE is LOW.
SDRAM clock output. Also, active LOW control input to stop CPU clocks, enabled
when MODE is LOW.
SDRAM clock output. Also, active LOW control input to power down device, enabled
when MODE is LOW.
SDRAM clock outputs
Active HIGH Output Enable Input (see table below)
CPU clock outputs
PCI clock outputs, at one-half the CPU frequency
Free-running PCI clock output
IOAPIC clock output
Reference clock outputs, 14.318 MHz, drives 45 pF load
Serial data input for serial configuration port
Serial clock input for serial configuration port
Mode Select pin for enabling power management features
Description
LOAD
Hi-Z
33.33 MHz
= 18 pF.
–195
PCICLK[0:5]
PCICLK_F
PPM
2
CPU and PCI Clock Driver Strengths
• Matched impedances on both rising and falling edges on
• Output impedance: 25
the output drivers
Hi-Z
14.318 MHz
IOAPIC[0:1]
REF0
(typical) measured at 1.5V.
CY2275A