22-30V input regulated to 20-22V output

Thread Starter


Joined Nov 29, 2015
Hello. I need to regulate the voltage (22V - 30V) and step it down to 20-22V. I am not able to use LDO voltage regulators due to the fact that they have high forward voltage drop and at arround 22V input I may not be able to get 20V output.

An interestng option I have found is this voltage regulator chip: http://www.ti.com/lit/ds/symlink/tps7a47.pdf
Considering that my input voltage should never be below 22V, I should be able to achieve 20.5V output considering its low forward voltage drop.

Have you got any other suggestions how to achieve 20-22V output from 22-30V input whilst keeping it as simple as possible?


Joined Mar 14, 2008
If you can tolerate the 300mV or so dropout voltage of the TPS7A470x regulator, than that should work for you.
It would mean that the maximum output for a 22V input would be about 21.7V.


Joined May 20, 2015
The circuit of the regulator I propose allows to get a minimum difference between the input and output of 10 mV at the current of 0.5 Ampere. I.e. at an input voltage of 22 V it is possible to receive (adjust) 21.99 V at an output (at loading of 0.5 A).
Compare them. And be aware that the output of the pulse stabilizer may be high-frequency ripple and this stabilizer will be a source of electromagnetic interference.