Adding current load to PWM output circuit?

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gofastant
Posts: 1
Joined: Mon Apr 21, 2008 6:29 pm

Adding current load to PWM output circuit?

Post by gofastant »

Hi all, didn't think I'd be the first person to post here but I have a couple questions. I believe I read that the PWM output circuits are limited to 5 amps. Would it be possible to add an extra mosfet to increase this? I have an A/W intercooler pump that is rated for 8 amps at 12 volts (Jabsco Centripuppy). I've built a seperate PWM controller from Jaycar electronics that can handle 10 amps but I'd obviously rather use the GPIO for simplicity.

Also, I've never written any code besides intro to VB in college. Could I (or some nice people) write a code to turn the pump on at a certain coolant temp and relay the pump straight to battery at full throttle? I could accomplish this with a temp sensor and a throttle switch but I'd again, rather keep it simple.

Thanks,

antony
1990 VW G60, MS2 V3.0
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: Adding current load to PWM output circuit?

Post by Bernard Fife »

Antony,

I am not sure if the traces on the production board are capable of carrying a sustained 8 Amps. On the beta units, the VBx circuits can carry more current than the PWM circuits - they have thicker traces (and they can still do PWM). VB1 had extra heavy traces for the highest current rating. I'll have to ask Bill about the trace limits on the production boards.

Al has written general purpose code that does switching based on a number of inputs (including those measured in the GPIO itself and those sent from MS-II via CAN). I am documenting this code and need to write an INI for it yet, and I am doing this now. The draft code is here: http://www.megamanual.com/gpio/code.htm, new code will be uploaded shortly (the location will change, and will be linked from http://www.msgpio.com/manuals/)

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
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