[Gmecm] Quad Driver currrent capacity?

[Dig]

Thanks Hank.  I'm using it as motor speed control, so the on/off thing is out.

Thunkin' out loud...  

Anybody switched a solid-state DC relay at say, 32hz?
http://rocky.digikey.com/WebLib/Crydom/Web%20Data/EZ%20Series.pdf

I'm trying to avoid having to wire-up circuits, making PCBs, worrying about heatsinks, etc. Just wire it up, and go.

One way to find out, I guess...

Dig


----- Original Message ----
From: "dozierhc at aol.com" <dozierhc at aol.com>
To: gmecm at diy-efi.org
Sent: Friday, May 11, 2007 12:39:52 PM
Subject: [Gmecm] Re: Gmecm Digest, Vol 27, Issue 10

Dig...
 
I think they can individually handle about 3 to 3.5 Watts without an issue.
Unless you are using multiple at same time at high DCs or in an ON/OFF configuration.
The typical load driven is about 60 Ohms.
 
So P= VI, and I=V/R.  ===> P= (V^2)/R.
 
If V= 14 Volts (typical) and R = 60 Ohms, then Power is 196/60 or 3.2 Watts.
 
So now if you use 14 Volts and 3.5 Watts (max), you get I = P/V  ==> 3.5/14 = 0.25 Amps per pin.
 
I know there is some safety margin built in, but I do NOT think you can directly drive 6 to 7 amps @ 12V with a direct quad driver output.  I think you might want to possible use the Quad output and put a MOSFET transistor on its output.  I think thre might be room on a 749 or 7727/7730 ECM heat sink to  attach one and run the wiring to/from it so as to use the connector for this rather than an off-board solution if PWM.  Just make sure you use at least a 14gauge wire for your run.
 
If its ON/OFF, then I would use an external relay...
 
Hank

----------------------------------------------------------------------

Message: 1
Date: Fri, 11 May 2007 09:11:27 -0700 (PDT)
From: Dig <turbodig at yahoo.com>
Subject: [Gmecm] Quad Driver currrent capacity?
To: gmecm at diy-efi.org
Message-ID: <852261.97481.qm at web35312.mail.mud.yahoo.com>
Content-Type: text/plain; charset=ascii

Apologies if this is a FAQ... searched the twiki and the archives, couldn't find 
anything conclusive.

Anyobdy have an idea about how much current capacity the quad drivers in a 
'749/'730 have?  Will they take amps or are they millamp devices.

I'm looking to PWM drive about 6-7 amps, would prefer not having external 
circuitry, but if I gotta, I gotta.

Thanks,

Dig
turbodig (at)yahoo.com
code59.org team nerd
RIP Bruce



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End of Gmecm Digest, Vol 27, Issue 10
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