I have a customer who is using this part to drive LEDs. It looks like the P port outputs can directly drive the standard SMD LED (less than 20mA forward current), Please confirm this is correct? If so, do you recommend to use the ports to drive the current or sink the current?
Please let me know.
Thanks, John Garrett, TI-AFA
Hello John,
It may be able to do that on the bench at room temp but you need to take more into consideration to make sure our part will operate properly over the desired operating range.
What supply are they operating at? How many LEDs are they planning to use at once? What is the temp range the device is going to experience? Will there be other devices on board that could have proximity effects for localized heating? What is the characteristics of the LED (a datasheet would be helpful)? The drive current might vary drastically over the temp range and with the amount of power dissipated. If you are going to drive 20mA, then I would suggest using more than one port at a time.
As you can see from the specifications you can't do more than 25mA per I/O if you maintain Tj less than 65C. I would recommend having the I/O pull down on the LED. The pull down strength is stronger, in other words the FET has lower resistance. Let me know if you can get more information about the application then we can make a more informed decision.
-Francis Houde
