DC/DC switcher for 5v TO 3v at 750mA in a TO-220 7805 footprint


An open source small DC/DC 3W switcher to drop 5V to 3V in a 7805 TO-220 pinout from Black Mesa Labs:

This post is an open source hardware design from Black Mesa Labs for a simple DC/DC converter for dropping 5V to 3.3V ( or adjustable to lower voltages via resistor selections ). The design is based on the PAM2305 from Diodes Incorporated, a great little 1 Amp step-down DC-DC converter in a small TSOT25 package. The PAM2305 supports a range of input voltages from 2.5V to 5.5V, allowing the use of a single Li+/Li-polymer cell, multiple Alkaline/NiMH cell, USB, and other standard power sources. The output voltage is adjustable from 0.6V to the input voltage.

More details at Black Mesa Labs site.

Join the Conversation

1 Comment

  1. Should BML put on Twitter that the board is a 3W switcher? It does not look like the board can do 3W stably…

    He managed to run it at 2.7W output, interesting, since say a 15% inefficiency * 2.7W gives 0.4W, the max thermal dissipation of the package. Personally, I would never run a TSOT switcher at its limits, no need to push my luck. He really needs a different package with that thermal pad and some thermal vias and a copper pour somewhere.

    Also, note that the 1V 1ohm demo, the efficiency is 61%. This is quite far away from the 70% estd from page 5 of the DS. Since the Vout ripple eqn gives 0.113A, methinks there is some coil saturation. But I am a coward anyway and I would never go near coil saturation loads.

Leave a comment

Your email address will not be published. Required fields are marked *

Notify me of followup comments via e-mail. You can also subscribe without commenting.