Partlist Wednesday: Voltage regulators

Every Wednesday we highlight a component from the updated partlist. This week: regulators.

This week’s part: voltage regulators. We try to use the cheap 150mA voltage regulators in SOT-23 package whenever possible. These are cheap (from 25 cents in 1s) and super resilient to shorts, over temperature, and over load. 150mA is enough for the vast majority of our projects, if we need more power we bump it up to a 800mA SOT-223. For lots of power (1A+), and/or high input voltages, we reach for the DPAK or D2PAK regulators.

Unfortunately there’s no standard part number for most regulators. We usually find new models by searching for “LDO” and the voltage (eg “LDO 3.3v”). There’s multiple models listed for common values on the wiki, they are usually interchangeable.

The post interface is giving us problems since the theme update, this week’s partlist post will be cut a bit short. Please fill in the gaps in with more tips in the comments.

Package guidelines:

  • SOT-23-5 (SOT-25): 2.9 mm × 1.3/1.75 mm × 1.3 mm body – five terminals
  • SOT-223: 6.7 mm × 3.7 mm × 1.8 mm body – four terminals, one of which is a large heat-transfer pad
  • DPAK (TO-252): discrete packaging. Developed by Motorola to house higher powered devices. Comes in three- or five-terminal versions
  • D2PAK (TO-263) – bigger than the DPAK; basically a surface mount equivalent of the TO-220 through-hole package.

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  1. For what it is worth, I have noticed many manufactures have 1117 series SOT-223 regulators, which tend to be rather inexpensive. TI REG1117; Fairchild FAN1117; On NCP1117; Diodes AP1117; Linear LT1117; etc. They are all the same thing more or less.

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