Help with power regulator design

Thread Starter


Joined Sep 10, 2021
Hi Guys,

I'm really struggling to get this sorted and my brains fried after this week.

I've had this design for a while and I'm getting a few built and everything seems great - fits where it needs etc.. I've suddenly had a horrible thought of the temperature consideration of this part though. Due to the application, I cannot afford the temperature to get to high as there is limited ventilation where it is to be installed. I have googled and researched this but cannot seem to get the right answer as to the temperature the below part will reach.


Can someone help me with this or advise of a low heat alternative? I've spent so much time on this and I'm stuck - HELP!


Joined Jun 4, 2014
Can someone help me with this or advise of a low heat alternative?
A linear regulator dissipates heat according to voltage across it and the current through it so any linear regulator will produce the same heat. You might add a heatsink which will help to transfer the heat to the air in the box, or even add a fan.

To get less heat you might reduce the input voltage or use a switch mode regulator.


Joined Aug 7, 2020
Power dissipated (Pd) = (Vin - Vout)*Iout
Vin = Vac * √2
Temperature rise = Ta + Pd*Rt
where Ta =ambient temperature
and Rt = thermal resistance.

This is true for any linear regulator


Joined Aug 1, 2013
Your have provided z.e.r.o useful information.

RMS input voltage
Peak output current
Links to datasheets for the bridge and regulator
Construction: surface mount or through-hole



Joined Jun 3, 2019
Anyone who makes designs and asks for help should know what WE need in order to help YOU. Just the very basic stuff like voltages and currents.. Looks to me that you havent sorted out the very basics of how this circuit works.