I gather the Analog Devices MAX666 equivalent would be the ADM666(A?). Any particular reason you decided not to use this? I am looking at a data aquisition system and was considering adding battery operation. I was thinking of using the configuration described in the ADM666A datasheets. In this the voltage regulator is connected to both external power and rechargable (NiCad in example) battery power. Through it's low voltage detects, it is used to automatically trigger trickle charging of the rechargable batteries of the power supply when they are low on charge. Due to the use of NiCad's it deischarges them through a LED first to prevent memory. I probably would have tried to use a rechargable cell without memory to allow trickle charging during normal mains powered operations. Were there any particular problems with the ADM666 that you found? Would they effect this application? Is there an easier\cheaper way to do this? Can anyone suggest a replacement for the Analog Devices voltage regulator? I live in Australia and have found Analog Devices parts very hard to source, which is a pity as they have a lot of nice looking products. Tom. ----- Original Message ----- From: William K. Borsum To: Sent: Tuesday, October 19, 1999 12:08 PM Subject: low Power Comparators--summary of findings > 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. > Original circuit used the Analog devices equivalent to the MAX666 regulator > with a comparator built in. > Hope this helps > kelly > > William K. Borsum, P.E. -- OEM Dataloggers and Instrumentation Systems > & San Diego, California, USA