can STM32F103 pins supply this much current in total?

[mehmet.karakaya]

Posted on February 10, 2017 at 09:43

hello dear forum,

I want drive 7 segment common cathode LED display with STM32F103

if I turn on all the segments 10 x 8 = 80 mA total

can the STM32F103 supply this much current in total?

thank you

[T J]

Posted on February 10, 2017 at 10:18

Yes, I think all pins can generally deliver 20mA, but the total is maximum about 100mA

so you are stressing the part...

you should use a buffer, like...

http://www.digikey.com/product-detail/en/nexperia-usa-inc/74HC9115D,112/568-2752-5-ND/1023027

then the processor will be fine...

I checked the data sheet, yes 25mA max per pin and 150mA max for the whole package...

but your not being nice...

it will get warm and the Vref will not be greatly accurate.. due to the excessive heat

are you reading any A/Ds ?

________________ Attachments : STM32F103.pdf : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HyxI&d=%2Fa%2F0X0000000bEM%2F_7BjUE.9kdqJfuRRDBocgWPxU_V9kfiDbsI58UCj1ac&asPdf=false

[David SIORPAES]

Posted on February 10, 2017 at 10:28

Yes, you can drive up to 20mA but with relaxed Vol/Voh except PC13, PC14, PC15 which can drive only 3mA.

See page 65 of the datasheet and table 36 for actual voltage drop numbers you will incur.