I mentioned I am playing with battery management. It is clear some interesting ICs out there. One of the problems is that there are so many ICs with so many variations, even if one just looks at one manufacturer like TI (who do some cool ICs).
So I thought I would try and explain what would be an ideal IC for some of my projects. From what I can tell this is all available in various ways with various ICs but not as one simple IC. I am not actually asking for much, honest. I have some of this pretty closely now but in a lot more components than is ideal.
There are some monster large QFN power management ICs out there as well, which seem overkill, and not sure I have yet found one with the "button" aspect.
So here is the list of what I would really like.
- A small IC, probably not actually BGA, but small, a QFN package or even small SOP style if few enough pins. It does not need a lot of pins for what I am talking about. TI have some funky QFN style packages with larger pads for the power, that would be fine. Ideally not special handling at PCB manufacturer (hence not BGA).
- A 3.37V LiPo connection for one LiPo cell.
- A 5V power input connection, i.e. from USB.
- A regulated 3.3V output - ideally 1A but at least 500mA. Can be switched off.
- A simple push button input (see below). Maybe also button state output pin.
- An I2C interface (see below).
- Perhaps even a "reset" output, that rises once power has stabilised, drops before power off - this saves a couple more passives.
- Perhaps even a LED output (I don't really need this).
Now the idea is simple, this provides both regulation for 3.3V working of a device, running from 5V and/or 3.7V LiPo, but also provides battery charging for the LiPo from 5V. There may need to be a pin to define charge rate, and even a pin for voltage output, but a fixed 3.3V saves more passives.
The regulated output could be a simple LDO type thing, or perhaps a synchronous step-down with integral FETs and small external passives. Minimal passives is ideal. Needs to run off 5V or 3.37V, i.e. work when there is no LiPo.
The idea of the button is simple. The device would have off or on modes. When off, and just on LiPo, its current needs to be a few uA at most, and no 3.3V output. But the button is used to turn on. The button could also have a last ditch "hold for 10 seconds" power off to allow it to be used as a system reset. It makes sense to turn "on" when powered up, and when 5V applied, as processor can decide to turn off if not needed.
I2C would allow checking state of battery, and 5V. Ideally an ADC for battery voltage, maybe even for 5V supply voltage too. Needs a way to check button state so it can be used when on for other functions, or perhaps a pin output to mirror the button. Needs a way to tell the device to go to "off" mode. A pin output mirroring button is probably best as this allows for processor (e.g. ESP32) in low power sleep when this chip is "on" and still use button to "wake up". There could be some special power regulation modes for extra low power but still "on" perhaps to allow this type of working as well as a proper "off".
I can't help feeling this fits the needs of a wide range of small battery operated devices.
If anyone knows of devices that tick some of these boxes, please do let me know.
Oh, and reverse polarity protection and reporting, therm al shutdown, etc.
