1 Introduction

Open any power module data sheet and its front page will advertise the module’s load current capability and input and output voltage range. A module with selectable or adjustable switching frequency will advertise its frequency options on the data sheet front page as well. In reality, not all input voltage, output voltage, load current, and switching frequency combinations can be achieved due to timing, current, and thermal limitations. One must look further into the datasheet to better comprehend the module’s valid operating conditions.

Power module data sheets include tables and graphs that summarize the maximum load current capability for different input and output voltage ranges, and different switching frequencies, if selectable/adjustable. An example of such a table is shown in Table 1-1 for the TPSM5D1806, which is a dual 6-A output buck power module with four selectable switching frequencies: 500kHz, 1MHz, 1.5MHz, and 2MHz. With this table, one can quickly determine the possible switching frequency choices for a desired input to output voltage conversion and max load current requirement, without needing to perform any calculations and analysis by hand or experimentally. Furthermore, module data sheets provide Safe Operating Area (SOA) curves, which show the maximum allowed ambient temperature versus load current as measured on the evaluation board (EVM), as an aid to quantifying the thermal capabilities of the device.

While these data sheet tables and graphs are useful for quick analysis and assessment of the device’s capabilities, they may leave an engineer wanting a deeper understanding of how the operating boundaries of the module have been determined. This understanding can aid an engineer in better selecting, comparing, and configuring power modules for their designs.