Mark,

I have had good success with the Linear LT1121 series of low-dropout linear
regulators... I-sub-q is somewhere in the 50uA range, I recall.

For really low-power, long-life battery operations, consider going to a
step-down switching regulator with an automatic shut-down under low-load
conditions... for example, the LTC1735 would fit the bill nicely.

mcb



At 12:09 PM 02/10/2000 -0600, Mark Peterson wrote:
>I am running a small circuit that includes a PIC off of a 24 VDC battery
>system.  I am minimizing my current draw by having the PIC sleep most of
>the time.  I wake it up every few seconds, have it power up the analog
>input conditioning circuitry, make its decisions, send an output signal if
>required, and then have it go back to sleep.  Current draw using this
>scheme is peanuts.  My problem is the quiescent current that a classic 7805
>regulator uses, roughly 3.5 mA.  I saw the earlier messages about the Maxim
>and TelCom regulators.  They look great but their maximum input voltage is
>around 11 volts.  I've considered various dropping resistor and zener
>schemes to use in conjunction with one of the low power regulators but they
>all end up sucking up as much current as the original 7805.  Any clever
>ides out there on this?
>
>Thanks.
>

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