I've done a few designs recently that are powered from a single 3.7V lithium cell which is recharged from USB. The design has always ended up with several ICs and a few discrete FETs and diodes to do the power ON/OFF switch.
Does anybody know of a single IC with the following features:
- Battery under/over voltage and over current protection, the equivalent of a DW01 and SC8205.
- Charging from 5V at up to 500mA, with the current set by a resistor. A status output for charging complete would be useful. The equivalent of an MCP73832 (or many other parts).
- An 'Output' pin which is connected to 5V when the 5V supply is present and to the battery when the 5V supply is not present, with zero voltage drop from the battery to the output.
- An active low enable input which turns on the Output pin. The battery should continue to charge with the output disabled.
Some nice additions would be:
- Multiple enable pins. One for a switch to initially turn on power, a second for a processor to hold power on until it's ready to switch off. The processor needs to read the state of the switch so I can't just bypass it with a FET.
- A switched battery output for voltage monitoring, turned off when the output is off to avoid discharge via the monitoring circuitry.
I can get '1' if I use a protected cell but it would be nice to not have to rely on that. I can get '2' & '3' by using something like an MCP73871. I can't quite get '4' as the enable pin also disables charging when the output is off.
This application can't be that uncommon, it seems like there should be a single part which does this, probably in something like an SO-8 package.
Dave.