What is the expected current taken by an unprogrammed STM32F4?

sandandstars · ‎2022-02-15

I have my own board and it wants to take >20mA at 3V3. I don't want to increase the current limit if there's a short, but I don't know what it needs. What sort of current should I expect before I program it? Thanks

waclawek.jan · ‎2022-02-15

Unless it's in bootloader (based on BOOT0 pin state), it's running at HSI=16MHz, no peripherals enabled, based on this you should be able to find the value in datasheet (there are many 'F4). Plus current taken by whatever else you have on that board, of course.

Even in bootloader it shouln't be much higher, until activity on some pin makes it to enter one particular peripheral mode.

JW

sandandstars · ‎2022-02-15

Thanks for your quick response. I had been wondering if it would be in stop mode or something. Still, it looks like 20mA is too much. Thanks again.

Uwe Bonnes · ‎2022-02-16

Some GPIO not external defined may float and draw current. F4 resets (most) GPIO to input. L4 resets to analog, so floating input does not harm.

sandandstars · ‎2022-02-16

Thanks Uwe. I disconnected all the other things, including the voltage reg. The F407 seems to take about 17mA when unprogrammed, which is more than the datasheet suggests. (Yes, the L0s hardly take anything.) Anyway I can program it ok now.