7A
CY2277A
Pentium®/II, 6x86, K6 Clock Synthesizer/Driver for Desktop/
Mobile PCs with Intel® 82430TX and 2 DIMMs or 3 SO-DIMMs
The CY2277A has power-down, CPU stop and PCI stop pins
for power management control. The CPU stop and PCI stop
are controlled by the MODE pin. They are multiplexed with
Features
• Mixed 2.5V and 3.3V operation
• Complete clock solution to meet requirements of Pen-
SDRAM clock outputs, and are selected when the MODE pin
is driven LOW. Additionally, these inputs are synchronized
on-chip, enabling glitch-free transitions. When the
CPU_STOP input is asserted, the CPU outputs are driven
LOW. When the PCI_STOP input is asserted, the PCI outputs
(except the free-running PCI clock) are driven LOW. Finally,
when the PWR_DWN pin is asserted, the reference oscillator
and PLLs are shut down, and all outputs are driven LOW.
tium®, Pentium® II, 6x86, or K6 motherboards
— Four CPU clocks at 2.5V or 3.3V
— Up to eight 3.3V SDRAM clocks
— Seven 3.3V synchronous PCI clocks, one free
running
— Two 3.3V USB/IO clocks at 48 or 24 MHz, selectable
by serial interface
— One 2.5V IOAPIC clock at 14.318 MHz
— Two 3.3V Ref. clocks at 14.318 MHz
• Factory-EPROM programmable CPU, PCI, and USB/IO
clock frequencies for custom configuration
The CY2277A outputs are designed for low EMI emission.
Controlled rise and fall times, unique output driver circuits and
factory-EPROM programmable output drive and slew-rate en-
able optimal configurations for EMI control.
• Factory-EPROM programmable output drive and slew
rate for EMI customization
CY2277A Selector Guide
-12/
• MODE Enable pin for CPU_STOP and PCI_STOP
• SMBus serial configuration interface
• Available in space-saving 48-pin SSOP and TSSOP
packages.
-12M/
Clock Outputs
CPU (60, 66.6 MHz)
CPU (33.3, 66.6 MHz)
-1/-1M
-3
--
4
-7M
4
-12I
4
--
--
4
--
--
Functional Description
CPU (SMBus select-
able)
--
--
--
The CY2277A is a Clock Synthesizer/Driver for Pentium, Pen-
tium II, 6X86, and K6 portable PCs designed with the Intel®
82430TX or similar chipsets. There are three available options
as shown in the selector guide
PCI (CPU/2)
7[1]
6/8
2
7[1]
6/8
2
7[1]
6/8
2
7[1]
6/8
2
SDRAM
The CY2277A outputs four CPU clocks at 2.5V or 3.3V with up
to nine selectable frequencies. There are up to eight 3.3V
SDRAM clocks and seven PCI clocks, running at one half the
CPU clock frequency. One of the PCI clocks is free-running.
Additionally, the part outputs two 3.3V USB/IO clocks at 48
MHz or 24 MHz, one 2.5V IOAPIC clock at 14.318 MHz, and
two 3.3V reference clocks at 14.318 MHz. The CPU, PCI,
USB, and IO clock frequencies are factory-EPROM program-
mable for easy customization with fast turnaround times.
USB/IO (48 or 24 MHz)
IOAPIC (14.318 MHz)
Ref (14.318 MHz)
CPU-PCI delay
1
1
1
1
2
2
2
2
1–6 ns 1–6 ns <1 ns 1–4 ns
Note:
1. One free-running PCI clock.
Pin Configuration
SSOP
Logic Block Diagram
IOAPIC (14.318 MHz)
Top View
V
DDQ2
REF1
REF0
AV
1
2
3
4
48
47
46
45
44
43
42
41
DD
REF [0–1]
(14.318)
PWR_SEL
XTALIN
14.318
MHz
OSC.
V
V
SS
DDQ2
XTALIN
XTALOUT
MODE
XTALOUT
IOAPIC
PWR_DWN
STOP
CPU
PLL
CPUCLK[0–3]
5
6
LOGIC
V
SS
V
CPUCLK0
CPUCLK1
7
8
9
10
11
DDQ3
V
DDCPU
PCICLK_F
PCICLK0
SDRAM[0–5]
V
SEL
40
39
38
37
36
35
34
33
32
31
EPROM
DDCPU
V
SS
CPUCLK2
CPUCLK3
PCICLK1
PCICLK2
MODE
SDRAM6/CPU_STOP
12
13
V
SYS
PLL
SS
PCICLK3
PCICLK4
SDRAM0
SDRAM1
14
15
16
17
18
19
20
21
22
23
24
SDRAM7/PCI_STOP
V
DDQ3
V
DDQ3
/2
PCICLK5
SDRAM2
SDRAM3
V
SS
Delay
SEL
V
PWR_DWN
STOP
LOGIC
SS
PCI[0–5]
SDATA
SCLK
30
29
28
27
26
25
SDRAM4
SDRAM5
PCICLK_F
SERIAL
SCLK
V
V
DDQ3
DDQ3
Divide and
Mux Logic
INTERFACE
CONTROL
LOGIC
USBCLK/IOCLK[0:1]
USBCLK/IOCLK
USBCLK/IOCLK
SDRAM6/CPU_STOP
SDRAM7/PCI_STOP
SDATA
V
AV
DD
SS
Cypress Semiconductor Corporation
Document #: 38-07332 Rev. *A
•
3901 North First Street
•
San Jose
•
CA 95134
•
408-943-2600
Revised December 7, 2002