LPCXpresso IDEのトピックRe: Add more current with 2 pins

Add more current with 2 pins

lpcware — Thu, 16 Jun 2016 01:41:26 GMT

Content originally posted in LPCWare by volter on Thu Jul 07 13:14:07 MST 2011
I have a Relay in my circuit and for get it work I need about 30mA.
As I know, all GPIO pins can generate 20mA so can I use 2 pins to control 1 part by simply connect them together :eek:?

Re: Add more current with 2 pins

lpcware — Thu, 16 Jun 2016 01:41:27 GMT

Content originally posted in LPCWare by Rob65 on Thu Jul 07 13:24:53 MST 2011
No,

that is a very bad idea.
Use a mosfet like a BS170 and a schottky diode .
If you value the correct working of your microcontroller you will never drive a relay directly from the I/O pins.

Rob

Re: Add more current with 2 pins

lpcware — Thu, 16 Jun 2016 01:41:27 GMT

Content originally posted in LPCWare by serge on Thu Jul 07 23:36:10 MST 2011
Isn't it so that for example the LPC1343 has only one (1) pin which can drive a led? Or did i misread the user manual?:confused:
And of course it is always better to use a fet or transistor to drive a relay.:p

Re: Add more current with 2 pins

lpcware — Thu, 16 Jun 2016 01:41:28 GMT

Content originally posted in LPCWare by Rob65 on Fri Jul 08 04:35:55 MST 2011
Serge is right.
I mostly use th lpc1754 so almost have forgotten about my nice lpc1343 boards...

The data sheet specifies:

[LIST]
[*]High-current output driver (20 mA) on one pin.
[/LIST]
So there is actually only 1 pin (PIO0_7) that is able to drive 20 mA. The other pins are limited to 4 mA (and no, it is still not a good idea to put 8 of these in parallel ;))