The Combination of Thermal and Electrical Improvements in a 1U 100A VRM

The voltage regulator module (VRM) has been the standard in higher-power computers for some time thanks to their better cooling capability and less use of motherboard space compared to VR down. Physical size keeps diminishing to allow for more space savings and so the trend is to go for a small form factor such as 1U. The scaling down of CPU voltages demands more current from the VRM to meet ever-increasing power levels. This paper presents some low-cost methods for improving thermal capability while still allowing for excellent electrical design. The use of these combined improvements led to a 9% decrease in peak device temperature and 18% decrease in system average temperature which is enough to eliminate the need for a heat sink with 400 LFM airflow, 25degC ambient and no derating. The VRM is used as an example but the process is generalized so that it can be applied to may other systems.