Bob Blick wrote:

> 
> Debbie wrote:
> 
> 
>>The dilemma -->
>>They come in a standard version that works on 5V but its quiescent drain is
>>170uA to 300uA
>>
>>However, they now offer an ultra-low standby current version that's rated at 46
>>to 60 uA quiescent.
>>
>>That's MUCH better for a battery operated device. BUT, the ultra-low Iq version
>>only works on 3V.
>>
>>Okaaaay, I have a 12V, 7.5Ah system and the PIC's (16F84) voltage is regulated
>>down to 5V using a 78LS05. Not sure what its standby drain is but must be
>>pretty low as the battery lasts for weeks.
> 
> 
> Doesn't the 78LS05 consume about 3 milliamps? You could save some 
> current right there using a better regulator on the 5V side.

Just about ANYTHING is better than a 78L05 for Iq.
Look at the LM2931-5 LDO regulators.

I think they also have a 3.3V version.

If you have nothing for current, why not just use a series 2V zener or
3 silicon diodes to get you the needed drop.

And can you strobe the sensor power (power it off a PIC pin, with diodes)
to save even more power?

Robert

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