Voltage Regulator Module (VRM) and Enterprise Voltage Regulator-Down (EVRD) 10.2 Design Guidelines

Voltage Regulator Module (VRM) and Enterprise Voltage 23
Regulator-Down (EVRD) 10.2 Design Guidelines
4 Input Voltage and Current
4.1 Input Voltages - EXPECTED
The power source for the VRM/EVRD is 12V +5% / –8%. This voltage is supplied by a separate
power supply. For input voltages outside the normal operating range, the VRM/EVRD should
either operate properly or shut down.
4.2 Load Transient Effects on Input Current -
EXPECTED
The design of the VRM/EVRD, including the input power delivery filter, must ensure that the
maximum slew rate of the input current does not exceed 0.5 A/µs, or as specified by the separate
power supply.
Note: In the case of a VRM design, the input power delivery filter may be located either on the VRM or
on the baseboard. The decision for the placement of the filter will need to be coordinated between
the baseboard and VRM designers.
It is recommended that the bulk input decoupling be placed on the baseboard by the VRM input
connector and high frequency decoupling on the VRM module. Expected baseboard decoupling
should be between 1000 µF to 2240 µF depending on VRM design and system power supply.
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