cy2256 Cypress Semiconductor Corporation., cy2256 Datasheet - Page 2

• Manufacturer Part Number: cy2256
• Description: Pentium Cyrix 6x86 Compatible Clock Synthesizer/driver Opti Viper Chipset
• Manufacturer: Cypress Semiconductor Corporation.

Pin Summary
Function Table
Name
V
XTALIN
XTALOUT
V
S2
CPUCLKA0
CPUCLKA1
V
CPUCLKA2
CPUCLKA3
V
S1
S0
V
CPUCLKB0
PCICLK0
V
PCICLK1
PCICLK2
V
PCICLK3
PCICLK4
V
PCICLK5
PCICLK6
V
REF1
REF0
0
0
0
0
1
1
1
1
Notes:
1.
2.
DD
SS
DD
SS
DD
SS
DD
SS
DD
S0
For best accuracy, use a parallel-resonant crystal, C
TCLK is a test clock on the XTALIN input during test mode.
[1]
0
0
1
1
0
0
1
1
[1]
S1
0
1
0
1
0
1
0
1
S2
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
XTALIN
Input
–
Description
Voltage supply
Reference crystal input
Reference crystal feedback
Ground
CPU clock select input, bit 2 (internal pull-up resistor to V
CPU clock A output
CPU clock A output
Voltage supply
CPU clock A output
CPU clock A output
Ground
CPU clock select input, bit 1 (internal pull-up resistor to V
CPU clock select input, bit 0 (internal pull-up resistor to V
Voltage supply
CPU clock B output
PCI clock output
Ground
PCI clock output
PCI clock output
Voltage supply
PCI clock output
PCI clock output
Ground
PCI clock output
PCI clock output
Voltage supply
Reference clock output (14.318 MHz)
Reference clock output (14.318 MHz)
50.0 MHz
50.0 MHz
60.0 MHz
60.0 MHz
66.66 MHz
75.0 MHz
66.66 MHz
High-Z
LOAD
CPUCLKA
= 18 pF.
50.0 MHz
50.0 MHz
60.0 MHz
60.0 MHz
66.66 MHz
75.0 MHz
High-Z
High-Z
2
CPUCLKB
25.0 MHz
33.33 MHz
30.0 MHz
33.33 MHz
33.33 MHz
33.33 MHz
33.33 MHz
High-Z
PCICLK
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
High-Z
DD
DD
DD
Ref. Clock
)
)
)
Output
Synch.
Asynch.
Synch.
Asynch.
Synch.
Asynch.
Synch.
PCI Mode
CY2256
–