I have an hardware question about stm32 family.

I am designing a circuit with STM32F103VB. datasheet mentions that i can draw up to 25 mA current per pin(page 37 table 7). I need to drive 40 npn bjts with mcu. if I draw 15 mA current from 40 pin at the same time, what will happen? same table says that i can draw 150 mA total from power lines.

it is 40*15 = 600 mA total. it's more than half an amp. will it damage the mcu? how much current can i draw per pin for driving bjts at the same time?

  • \$\begingroup\$ The clue is in the power pin current limitation. \$\endgroup\$
    – Andy aka
    May 27, 2019 at 14:19
  • 1
    \$\begingroup\$ I would simply use N-channel MOSFETs in stead of BJTs. \$\endgroup\$ May 27, 2019 at 14:26

1 Answer 1


Page 37 has clear limits for max current.
You will have to reduce your current by /8 to drive 40 outputs.

  • \$\begingroup\$ That was going to be my answer! Buffer the outputs with the appropriate 74xx series, or select super-beta transistors, or use Darlingtons, or use logic-level FETs. \$\endgroup\$
    – TimWescott
    May 27, 2019 at 15:12

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