Re: Need help driving two IPS1031 Low-Side MOSFETs from a PIC

On 11 Aug 2006 21:10:39 -0700, the renowned JedOs86@xxxxxxxxx wrote:

Ok I "decypherd" your schematic LOL. But in your schem your mixing the
signals, If i were to do this, the relay would be on whenever a signal
was enterd. The 2 diodes allow for the relay to go on when only one
specific signal is enterd.

The PIC outputs actively drive low as well as high*, and the 130uA or
so that the "low" relay drive output sinks when it is off, and the
other output is on, is not high enough to cause problems. The base
resistors could be increased from 4.7K to 10K, 20K or 30K without
problems.

If it really bothers you, it would be better to use two 2N4401s in
parallel to drive the 5K load than to add diodes (one less part etc.),
but it's not necessary.

*Unless deliberately tristated, but that's an unlikely situation.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@xxxxxxxxxxxx Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
.

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