0
\$\begingroup\$

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?

\$\endgroup\$
2
  • \$\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\$
    – Bimpelrekkie
    May 27, 2019 at 14:26

1 Answer 1

Reset to default
0
\$\begingroup\$

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

\$\endgroup\$
1
  • \$\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

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.