Help with selecting charging IC for LiPo battery charge management

Question

I have a project for which I have a 1 cell LiPo battery, and of course I need a BMS to monitor it and charge it/ensure it doesn't get discharged too far. I also want LED indicators to inform of the charge state of the battery, and a boosted output of 5V is also needed.

However another important thing to note, I will have a load of ~120mA when active, and this load I want to toggle exclusively with with a SPST-NO switch.

All this in mind, I first came across the IP5306, and this example circuit.It seemed close to perfect but then I noticed this line

If button is pushed longer than 30ms but shorter than 2s, IP5306 will identify the action as short push. Short push will activate state of charge (SOC) indicator LEDs and step-up converter.

And unfortunately that ruled that one out, as I couldn't find a work around to this, as I want to only have to control the output with the switched mentioned previously.

I also did some reading on the TP4056 and BQ24075 ic's, and while this could be an approach for the charging side, I am not sure how to create the indication of the charge for it elegantly without the usage of micro controllers, which I would rather avoid if possible.

So now I am wondering if there is even any IC like the IP5306 but without that one shortcoming, or is there some elegant way to achieve the required result with different ic's, or would I just be better of finding a small MCU ?

Answer 1

Perhaps there is another IC that has everything you want, but 'shopping' questions are off-topic here so you will have to look for it yourself. Furthermore, even if you do find an IC that has everything you want, there's no guarantee that this chip will always be available. So unless you are only making a 'one-off' I don't recommend tying the design to a particular IC.

The IP5306 appears to be a fairly generic 'Power Bank' IC that operates similarly to others. A short button push turns the output (and indicator LEDs) on, and a long push turns it off. If you could simulate this action from a toggle switch then it may do the job for you. One way to do it could be to use a small MCU such as a PIC10F322 (which draws less than 1 uA in sleep mode) programmed to convert the on/off switch to short/long pulses.

Alternatively it might be possible to simulates button presses using a digital logic IC and RC timing - something like this:-

^{simulate this circuit – Schematic created using CircuitLab}

However this circuit has less accurate timing and uses a lot more parts than the MCU solution.

Or, as you say, it might be better to use an MCU to provide all the functionality you need, including battery charge indication and perhaps even charging and boosting. That way you can make it operate however you like without restrictions, and can use whatever charger and booster circuit works best. This will require a lot more design effort, but could be worth it for easier customization and improved efficiency.

On the other hand, do you really need that on/off switch action? Most users today are familiar with the short/long button push method.