switch up to 5V and 8 mA with MSPM0 Open Drain IO

RE: switch up to 5V and 8 mA with MSPM0 Open Drain IO

DAB — Thu, 20 Nov 2025 21:00:51 GMT

Nice post Jan.

RE: switch up to 5V and 8 mA with MSPM0 Open Drain IO

Jan Cumps — Wed, 19 Nov 2025 18:53:01 GMT

The open drain output controlled by MSP0 PWM:

[View:https://youtu.be/ET9UlfqYezY:640:360]

RE: switch up to 5V and 8 mA with MSPM0 Open Drain IO

jc2048 — Wed, 19 Nov 2025 10:45:00 GMT

You're quoting the 20mA from the absolute max ratings table. The IOL is 8mA (see the table further down the datasheet).

That 20mA basically comes down to a dissipation limit for the output transistor (20mW is quite a lot in a small area on-chip) - the metallisation and the bond wires will manage much more than that before fusing.

Your example is no problem at all because you're only running about 7.5mA through the red LED (not 10mA - you haven't taken into account the rDS-on value for the output MOSFET), and you're pulsing it at intervals which reduces the average dissipation even further. But sinking 20mA DC for a backlight with it wouldn't be good design practice, though it could work for a personal project (the ratings are somewhat conservative and you're not going to be operating it in an ambient temperature anywhere near the top of the spec range, anyhow).

RE: switch up to 5V and 8 mA with MSPM0 Open Drain IO

shabaz — Tue, 18 Nov 2025 21:41:16 GMT

That's very neat! Awesome that the microcontroller has this feature. Since it also follows that the input for those pins must be 5V tolerant too, then it would be easy to use the microcontroller to interface with legacy 5V protocols like 1-wire and so on, with no extra components either. And the ability to directly drive MOSFETs (for at least some use-cases) with the higher 5V rather than 3.3V is also extremely useful.