Hello MPS Heroes!
I’m planning to use the excellent MP2672A in standalone mode, but I need a way to enable/disable battery charging.
This control is available through bit 4 of REG00H in the I2C interface but I’m not using this interface (standalone configuration), and there is no dedicated enable pin on the device.
I was thinking of using an external FET to short or open circuit one of the resistors in the NTC circuit, or maybe the VLIM pin?
If there is an elegant and proven way to do this, I’d be grateful to hear about it.
Ta muchly, Rob.
Well, I have solved my own problem, so I post my findings here for the benefit of others…
An inexpensive, simple way to disable charging on the MP2672A in standalone mode is to ground the NTC pin via an N-channel MOSFET. I used a 2N7002 with source to ground, drain to NTC pin, gate to active high charge disable signal.
When gate is low the NTC compensation circuits works unaffected; when gate is high NTC is grounded simulating an over-temperature condition which inhibits charging.
Works a treat!