Since several of you asked for my findings on low power comparators, here goes: History: Original requirement was for a low battery voltage detector circuit for a PIC based data logger. 9.5 volt batteries could decay to around 6.8 volts before the combined diode and regulator drops would allow the analog references to loose stability. Total power consumption was between 45 and 70 uA in "quiescent" mode, which would give a year or more life off a standard alkaline radio battery. Original circuit used the Analog devices equivalent to the MAX666 regulator with a comparator built in. The newer circuits used the TC55 series regulators, and a LMC7225 comparator which (in theory) would take the quiescent current through those parts from around ten uA to 2-3 uA--a better than 10% savings in power usage. However, the LMC7225 turned out to be available ONLY in reels of 1000, with an 8-12 week lead time--which was not true when the board was designed several months ago. (There is a lesson here!) Findings: First thought was to go with a 3-pin voltage detector (reset circuit) from Telcom--the TC54 series which is carried by digikey. Problem was--dropping the battery voltage through a divider required about 100uA for the TC54 to maintain stability due to its low input impedance (3-4 MOhms)--and a nasty habit of jerking the input impedance around when switching output levels which led to some very obnoxious oscillations. One of you all suggested the MAX918 for an open collector unit, which is what was being replaced. Ended up with a MAX917--available off the shelf from Maxim Small Orders (minimum quantity of 25 at $1.90). Unit has a built in reference, and a bias current of < 1 nA--which allowed the use of very large divider resistors, and a divider current of 1-2 uA. Using a device with a push-pull output also eliminated the pull up resistor on the output, and a bit of other power hungry circuitry. Most of the power consumption is still in the divider network. Hope this helps kelly William K. Borsum, P.E. -- OEM Dataloggers and Instrumentation Systems & San Diego, California, USA