UV1V10F5 slow startup time

I have a Pololu #2564, U1V10F5 to convert 2 AA battery voltage to 5V. The device to be powered is a Teensy 3.2 processor board. I’m having a problem using just battery power. If I start the processor using a USB cable then, with the battery connected, remove the USB cable everything continues to run. That tells me the battery power circuit can supply the 5V at the current required by the processor.

The regulator is too slow to go from 0V to 5V. The oscilloscope has a dc offset that makes it appear the 5V is 5.56V but my voltmeter reads 5V. The problem is how slowly it ramps up. Between the two vertical red lines is 30.8 ms. The time between power on and 5V is 56ms. Is there any way to shorten this startup? Is there another up regulator of about the same size that ramps up quicker?

U1V10F5 startup


I moved your post to the voltage regulator section of our forum.

It sounds like the Teensy is drawing a burst of current at startup that the batteries or regulator cannot handle. The soft-start feature of the U1V10F5 regulator limits the output current as the output voltage rises to limit overshoot or spikes. Could you try looking at the start-up time with no load on the regulator? How much current does your Teensy draw? Is there anything else attached to the 5V output of the regulator or to the Teensy? Could you post pictures of your setup that show all connections?


thanks for the reply. I’ll set up a testbed and get the measurements and post a reply with those details.

I did some testing and after ruling everything else out I replaced the regulator. The new one powers on almost instantaneous. The old one did regulate but it was 40-50 ms to power up which is why I could power up via USB then disconnect. By then the battery-regulator was up to full voltage. I did measure the current that my circuit took – 20ma.

That is an interesting behavior for a damaged regulator. I am glad you were able to resolve the issue!