pivden 6 Posted August 25, 2014 Share Posted August 25, 2014 simple question: DC Current per I/O pin MSP430G2xxx? previously found, now I can not find Quote Link to post Share on other sites
spirilis 1,265 Posted August 25, 2014 Share Posted August 25, 2014 Roughly speaking, don't push it over 8mA, and not more than a few at a time. Prefer to keep it <4mA even. bobnova 1 Quote Link to post Share on other sites
bobnova 59 Posted August 25, 2014 Share Posted August 25, 2014 I was wondering about this too. The datasheet is less useful than it could be. Thanks! Quote Link to post Share on other sites
spirilis 1,265 Posted August 25, 2014 Share Posted August 25, 2014 Basically, looking at page 25, you see (almost) everything you need. Right-side graphs (Vcc=3V), Typical Low-Level Output Current vs. Low-Level Output Voltage ... and Typical High-Level Output Current vs. High-Level Output Voltage. At 8mA, the port is outputting ~2.7V, and when sourcing 8mA the pin's voltage may rise to ~0.2V or so. If you feel you have some leeway there, you can try putting more current through it, but just beware on those graphs how the voltage may change. I think 8mA max is a good rule of thumb to keep things close to ideal. Page 24 indicates: (1) The maximum total current, I(OHmax) and I(OLmax), for all outputs combined should not exceed +/-48mA to hold the maximum voltage drop specified. So don't use more than 5 or 6 of them with those sorts of loads at a time, I say... Quote Link to post Share on other sites
rockets4kids 204 Posted August 25, 2014 Share Posted August 25, 2014 As Spirilis points out, there is no hard limit but you do need to be aware of voltage droop under loads greater than a few mA. Quote Link to post Share on other sites
bobnova 59 Posted August 26, 2014 Share Posted August 26, 2014 Yeah, that I'd found. I was surprised to not find a hard cap like Atmel specifies. Maybe it varies too much by chip or something. Quote Link to post Share on other sites
RobG 1,892 Posted August 26, 2014 Share Posted August 26, 2014 Look at figure 6-9 in the datasheet, it should make it clear why there's no hard cap. Quote Link to post Share on other sites
bobnova 59 Posted August 26, 2014 Share Posted August 26, 2014 They're roughly indestructible if you don't mind a large voltage drop? That's what those figures imply to me. Interesting. Atmel bits in this class start dying after 40mA according to their datasheet. Quote Link to post Share on other sites
tripwire 139 Posted August 26, 2014 Share Posted August 26, 2014 I expect you'd need to watch out for the thermal effects of that large voltage drop. Otherwise you might be inducted into the "Hall of Flame" Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.