Hi there. Im looking to use a MP2639A/C in an upcoming project, and I’m wondering if there is a recommended IC, or design, for pulling the MODE pin high/low depending on precense of a USB power in. I will require charge/discharge functionality, and would prefer not to use a switch.
Ideally, I am able to have bidirectional charge/discharge on the same 5v rail to minimize complexity.
Thanks for your time.
Hello @adunn,
The MODE pin in MP2639A needs to be pulled high/low during charging and discharging operation. The switch is the key component as connects either to GND or FB network at VH. VL or low voltage terminal indicates the presence of the USB input. Hence, without the switch, it will be difficult to have the desired mode of operation. I would recommend using MP2651 as the charging and discharging depends on the presence of input voltage
The MP2639A is desirable for my needs.
Ok so in that case, something like this is what’s expected for USB 5v sensing with the MP2639A?
Hello @adunn,
The use of transistor as switch which is controlled by the USB input seems fine as long as the VL, VH and Mode voltage thresholds are met for both charging and discharging. The resistor network must be tuned meticulously to achieve the required base voltage and the corresponding mode voltage.