>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>On Behalf Of Jinx
>Sent: 17 January 2007 00:22
>To: Microcontroller discussion list - Public.
>Subject: Re: [EE] B+ disconnect
>
>
>> If I can make what I think is a simple suggestion: use a capacitively
>> coupled charge pump on the FET gate(2 caps, 2 diodes) and then
>> have the 12F generate a pulse train when it wants the FET turned on
>
>> Advantage is that you get to use a great big beefy N-channel FET that
>> costs much less than a little wussy P-channel FET.
>
>Thanks Dwayne. I think I may have remembered incorrectly the 
>FET H-bridge. I'd have to look for it to be sure. Reading your 
>reply, and knowing that P-ch FETs aren't as common as N-ch, it 
>occurred to me that I may have had N-ch top and bottom, hence 
>needing 2 x
>V+ for the top gates

What kind of current drain are you expecting from the 12v SLA battery?  P channels MOSFETs can be had with pretty reasonable specs these days, and it makes things a simpler if you can avoid voltage doublers.

Regards

Mike

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