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3-Pin Switching Regulators

PostPosted: Thu Jan 16, 2014 8:41 pm
by Daniel

You may have noticed that there are two versions of the 3-pin switching regulator for sale, the PSU1 and PSU2. Both Regulators are available in 5V and 3.3V versions and I'm often asked what the difference is between the two regulators.
The PSU1 design is rated at 40V input and is more accurate than the PSU2 design. The PSU2 design is only rated at 17V on the input and is NOT suitable for use in an automobile because it does not survive the spikes present on the '12V' in a car. The PSU1 works well in cars and trucks.

The other major difference is the switching frequency; The PSU1 switches at 300kHz and the PSU2 at 3MHz. The larger inductor on the PSU1 has a bigger leakage field (it is not as well shielded) as the tiny inductor on the PSU2 and may cause more noise coupling to nearby circuits.


Re: 3-Pin Switching Regulators

PostPosted: Sun May 31, 2020 11:47 pm
by rhauff
I have purchased several of the PSU2-3.3 and plan to power ESP8266's in auto battery monitors, mainly during long term storage.
What is the quiescent current?
Since there is risk of destroying the PSU2-3.3 with spikes over 17V, I plan to install a series protection resistor of maybe 15ohms to a 15V zener to clamp the max voltage supply.
Thank you

Re: 3-Pin Switching Regulators

PostPosted: Sun Jun 07, 2020 10:50 pm
by rhauff
I have fried 2 of my PSU2-3.3 and not sure why. I am supplying 12.5V to the PSU2 from a battery, and using it to power a WEMOS D1 Mini by the 3.3V pin.

The first PSU2 worked for 2 power ups, then fried and also destroyed the WEMOS D1 mini.
The second PSU2 worked only on the first power up, then fried on the second and destroyed the WEMOS D1.

I have no other loads or circuits attached. The 1A rating of the PSU2-3.3 should be 3 times what is needed for this application.
What is going wrong? I only have 1 PSU2-3.3 left and am afraid to try it.