Voltage Regulator Module (VRM) 10.2L Design Guidelines

Voltage Regulator Module (VRM) 10.2L Design Guidelines 25

6 Output Indicators

6.1 Power Good (Vcc_PWRGD) - PROPOSED

The VRM may provide a power-good output signal, which remains in the low state until a

maximum of 10 ms after the output voltage reaches the range specified in Section 2.2. The signal

should then remain asserted as long as the VRM output is operating within specification. It will be

an open-collector/drain or equivalent signal. The pull-up resistor and voltage source will be located

on the baseboard. If this signal is not implemented on the VRM, it should be left unconnected.

Table 6-1 shows the Vcc_PWRGD pin specification.

6.2 Voltage Regulator Hot (VR_hot#) - PROPOSED

The VRM VR_hot# signal is an output signal that is asserted low when a thermal event is detected

in the converter. Assertion of this signal will be used by the system to minimize damage to the

converter due to the thermal conditions. Table 6-2 shows the VR_hot# pin specification. This

signal will be an open-collector/drain or equivalent signal and needs to be pulled up to an

appropriate voltage through a pull-up resistor on the baseboard. A typical implementation would be

a 50 ohm resistor pulled up to 1.2 V.

Each customer is responsible for identifying maximum temperature specifications for all

components in the VRM design and ensuring that these specifications are not violated, while

continuously drawing specified Icc (TDC) levels. In the occurrence of a thermal event, a thermal

sense circuit may assert the processor’s FORCEPR# signal immediately prior to exceeding

maximum VRM, baseboard, and/or component thermal ratings to prevent heat damage. The

assertion may be made through direct connection to the FORCEPR# pin or through system

management logic. Assertion of this signal will lower processor power consumption and reduce

current draw through the voltage regulator, resulting in lower component temperatures. Sustained

assertion of the FORCEPR# pin may cause noticeable platform performance degradation and

should not occur when drawing less than specified thermal design current for a properly designed

system.

Table 6-1. Vcc_PWRGD Specifications

Symbol Parameter Min Max Units

Output Low Current 0 4 mA

Output High Voltage 0.8 5.5 V

Output Low Voltage 0 0.4 V

Table 6-2. VR_hot# Specifications

Symbol Parameter Min Max Units

Output Low Current 19.9 30 mA

Output High Voltage 0.8 3.465 V

Output Low Voltage 0 0.4 V