Specifications

17 January 1997 – Subject to Change
Functional Description 4–19
Reset and Initialization
4.7 Reset and Initialization
A TL7702B power monitor senses the +3.3-V rail to ensure that it is stable before
+2.5 V is applied to the 21164 microprocessor. In normal operation, should the
+3.3-V rail fall below 2.5 V, the power monitor enables shdn_l, which turns off the
+2.5-V regulator (pc164.32).
An external reset switch can be connected to J24 (pc164.28). The reset function
initializes the 21164 microprocessor and the system logic. The p_dcok signal
provides a full system initialization, equivalent to a power-down and power-up
cycle.
In addition, the fan sense signal (fan_ok_l) is logically ORed with the reset switch
output and, when enabled, drives rst_l, indicating a fan failure.
The rst_l signal is buffered and drives a set of sys_reset signals to reset the
remainder of the system, including PCI and ISA devices through the CIA chip.