User manual

MIC-3392MIL User Manual 42
3.1 Introduction
The pre-heat feature provides an automatic control mechanism for the reliable cold
bootup of the MIC-3392MILC. Equipped with a heat pad on the conduction-cooled
plate and special BMC firmware for its control, if the ambient board temperature is
too low for stable power-on, the preheating circuit powers up the heat pad and keeps
the board in reset until the board temperature reaches a safe operating temperature.
An alternative pre-heat mode (user configurable) will additionally use the chipset and
CPU to generate power dissipation by de-asserting the reset for configurable time
intervals.
The cold boot control mechanism is only activated upon board startup and does not
perform monitoring during standard board operation.
A thermal sensor (DS1631AU) located between the CPU and the PCI-bridge on the
primary side of the board is used to monitor the ambient board temperature during
boot-up. The operating range of this thermal sensor is -55° C to 125° C.
Figure 3.1 Pre-heat thermal sensor (DS1631AU) location