13

Integrated

Circuit

Systems, Inc.

ICS952621

0756A—09/10/04

The time from the de-assertion of PD# or until power supply ramps to get stable clocks will be less than 1.8ms. If the drive

mode control bit for PD# tristate is programmed to '1' the stopped differential pair must first be driven high to a minimum of

200mV in less than 300

µs of PD# deassertion.

PWRDWN#

Tstable

<1.8mS

Tdrive_PwrDwn#

<300

µS, >200mV

CPU, 133MHz

CPU#, 133MHz

SRC, 100MHz

SRC# 100MHz

3V66, 66MHz

USB, 48MHz

PCI, 33MHz

REF, 14.31818

PD# De-assertion

The 3V66_4/VCH pin can be configured to be a 66.66MHz modulated output or a non-spread 48MHz output. The default is

3V66 clock. The switching is controlled by Byte 5 Bit 5. If it is set to '1' this pin will output the 48MHz VCH clock. The output

will go low on the falling edge of 3V66 for a minimum of 7.49ns. Then the output will transition to 48MHz on the next rising

edge of DOT_48 clock.

3V66

3V66_4/VCH

DOT_48

7.49nS min

3V66_3/VCH Pin Functionality