GPIO mA Drive Capability ?

[ChrisNielsen]

The DS shows +/-1mA for DSE=001.  Can you share mA values for the other DSE settings?  I'm hoping to be able to drive a few LEDs directly and need to understand the limits.

I do see that the Tower board drives these directly (PTB0-3) which is encouraging but I would like to be able to check the math.  Thanks, Chris

[ChrisNielsen]

It appears that this question didn't post to the Vybrid area.  It doesn't show in my activity area either.  Could the moderator please repost?  Thanks, Chris

[naoumgitnik]

Dear Chris,

While following note 1 of the Datasheet table you referred me to ("For details about Software MUX Pad Control Register DSE bit, see IOMUX Controller chapter of the device reference manual."), I found the data of interest in the "IOMUXC_PTA6 field descriptions" table.

The DSE bits describe internal resistance rather than output current, but the major point here is amount of heat dissipated inside the chip, so the 111 setting is the best in this case.

(BTW, nowadays LEDs are very efficient and quite bright even at units of mA.)

Regards, Naoum Gitnik.

[ChrisNielsen]

Yes, I too was concerned about internal heat and also damaging the bond wire with too much current (fuse).

Would it be possible to put a mW limit on a single pin's dissipation?  Or, on a "port" (PTA, PTB, etc)

Or, would it be possible to put an upper limit on the mA, say 25 mA as being a safe limit? (that's the highest I've ever seen on a microcontroller)

My application is considering mA < 10 so I won't be near the limits proposed above, but it would be good to know the limit(s) in case I need to drive a higher power device and would be able to compute if I can safely avoid the cost of a buffer (direct drive).

[naoumgitnik · Accepted solution]

Hello Chris,

On the Tower board it is about 6 mA; if not enough for your application, I can dig deeper (please, remember to use DSE = 111).

Sincerely, Naoum Gitnik.