Power supply review

There are many types of power supplies. This review summary is about DC-DC converters, which take one DC voltage and create a second DC voltage.

A good way to start a design review is by dividing the work into several pieces:

Does the specified circuitry match what the manufacturer intended? For example, are all the pins in the datasheet present on the schematic symbol? Are the pin numbers correct? Do the pin names match what the manufacturer specified?

Has the circuit been designed so that it will perform to specifications? Oh! What are the specifications? It is not uncommon to find a power supply design that hasn’t been completely specified.

Typical specifications would be

  • nominal, maximum, and minimum input voltage.
  • nominal, maximum and minimum output voltage
  • input voltage ripple (maximum).
  • output voltage ripple level (maximum)
  • output voltage ripple frequency
  • temperature range
  • allowable component temperatures
  • safety standard (if applicable)
  • EMC standard
  • component height
  • assembly constraints: surface mount only? Maximum height?

Another area to review: what are the component tolerances, and can they combine in such a way that the circuit will malfunction?

What are the transients which the circuit could be exposed to?

Could the circuit be miswired? If so, what faults can occur, and how are they protected?




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