D24V150F5 undervoltage

Hi, I’ve got a D24V150F5 15A 5.0V regulator, and it consistently outputs less than 5.0 volts. With my circuit having a typical quiescent draw of around 500mA and an input voltage of 18-21V (either a laptop power supply or an “18V” power tool battery), I’m seeing a very constant 4.92V from an INA260 sensor, with my multimeter showing 4.94V.

As the regulator is powering a Raspberry Pi, this is quite close to its lower limit and I often get under-voltage warnings. Is there some reason why it consistently delivers less than 5.0V? I’ve noticed this on smaller Pololu 5V regulators as well.

Given the actual voltage requirement of a Raspberry Pi is 5.1V (the same for all models) it’s a shame it’s not off by being higher than 5V.

Hello.

Due to various factors such as component tolerances, the output is rarely exactly the listed value, and there will be some unit-to-unit variation. For example, the tolerance on the output for most of our regulators is ±4% (as listed on their product pages); although we generally expect them to be better than that, as you’re measuring.

As you mentioned, Raspberry Pi boards typically work better with a voltage slightly higher than 5V. With the proper surface-mount rework tools and experience, you could change some resistors on the board to adjust the output voltage. If you would like to attempt that, please email us and refer to this thread and I will send you more details.

Brandon

Thanks Brandon,

This is for a robot and the D24V150F5 is your only 15A regulator,
hence the choice. If it’s possible to add a trimmer instead of fixed
resistors, I’d probably opt for that, and just hand-adjust it using
a multimeter. So yes, I’ll contact Pololu via email as suggested.

Thanks!