参数资料
型号: CY2280
厂商: Cypress Semiconductor Corp.
英文描述: 100-MHz Pentium II Clock Synthesizer/Driver with Spread Spectrum for Mobile or Desktop PCs
中文描述: 100兆赫奔腾II时钟合成器/有蔓延的移动或台式电脑驱动谱
文件页数: 1/12页
文件大小: 152K
代理商: CY2280
100-MHz Pentium
II Clock Synthesizer/Driver with
Spread Spectrum for Mobile or Desktop PCs
Functional Description
The CY2280 is a Spread Spectrum clock synthesizer/driver for
a Pentium II, or other similar processor-based PC requiring
100-MHz support. All of the required system clocks are provid-
ed in a space-saving 48-pin SSOP package. The CY2280 can
be used with the CY231x for a total solution for systems with
SDRAM.
The CY2280 provides the option of spread spectrum clocking
on the CPU and PCI clocks for reduced EMI. A downspread
percentage is introduced when the SEL_SS input is asserted.
The device can be run without spread spectrum when the
SEL_SS input is deasserted. The percentage of spreading is
EPROM-programmable to optimize EMI-reduction.
The CY2280 has 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.
CY2280
Cypress Semiconductor Corporation
Document #: 38-07207 Rev. *A
3901 North First Street
San Jose
CA 95134
Revised December 08, 2002
408-943-2600
0
Features
Mixed 2.5V and 3.3V operation
Clock solution for Pentium II, and other similar pro-
cessor-based motherboards
—Four 2.5V CPU clocks up to 100 MHz
—Eight 3.3V sync. PCI clocks, one free-running
—Two 3.3V 48-MHz USB clocks
—Three 3.3V Ref. clocks at 14.318 MHz
—Two 2.5V APIC clocks at 14.318 MHz or PCI/2
EMI control
—Spread spectrum clocking
—Factory-EPROM programmable spread spectrum
margin
Factory-EPROM programmable output drive and
slew rate
Factory-EPROM programmable CPU clock frequencies
for custom configurations
Available in space-saving 48-pin SSOP package
CY2280 Selector Guide
CY2280 Configuration Options
11S
4
8
2
2
3
1.5
4.0 ns
0.6%
Clock Outputs
1
4
8
2
2
3
21S
4
8
2
2
3
1.5
4.0 ns
2.0
4.5 ns
0.6%
CPU (66.6, 100 MHz)
PCI (CPU/2, CPU/3)
USB (48 MHz)
APIC (14.318 MHz)
APIC (PCI/2)
Reference (14.318 MHz)
CPU-PCI delay
CPU-APIC delay
Spread Spectrum (Downspread)
1.5
4.0 ns
N/A
Pentium is a registered trademark of Intel Corporation.
Logic Block Diagram
EPROM
XTALOUT
XTALIN
APIC [0:1]
1MHz
OSC.
SEL0
SEL1
V
DDAPIC
REF [0-2]
PLL
SEL100
SEL_SS
Delay
CPUCLK [0-3]
V
DDCPU
PCICLK_F
PCI [1-7]
STOP
STOP
USBCLK [0:1]
SYS PLL
CPU_STOP
PWR_DWN
Divider
PCI_STOP
V
DDPCI
V
DDPCI
V
DDREF
V
DDUSB
-1
-2
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