MP2696A use with microcontroller

Battery Management
1

Dear MPS technical team,

I’m trying to implement the topology depicted in the picture below:

image_2022-10-31_175917959
image_2022-10-31_175917959980×376 13.6 KB

And I was wondering if it’s actually possible as the Q2 transistor is OFF by default(REG 04h)?
Or what modification to the topology should be made to make it work.
I feel like i’m missing something in the datasheet

Thanks

2

According to the datasheet, BST_EN is off by default… Q2_EN is also off by default… It looks like the CPU should be attached to the battery and run off 4.6V instead.
Also boost mode is disabled in Vbat < 2.9V or Vin > 2V… Check these two.
And NOLOAD_THR is quite high… 30mA minimum.
Simon

Simon

3

Thank you for your answer Simon

if i plug it directly to the battery I’m scared that i will drain it during the shipping process

The idea is that the system is completely off during shipping process. When the 12-24V is plugged in, the system is powered then it stays ON as long as necessary, even without 12-24 supply. If the system decides that it needs to go completely OFF it should cut the boost and wait for the following 12-24 power.

Why is the NOLOAD_THR important in this case? Can’t i Just ignore it?

Thanks

4

NOLOAD_THR is monitored for turning on and off Q2 (by CPU).
I also would suspect, that the unit will be off until told otherwise.
QH is reverse biased so 0.6V drop, SMID is powered.
Then the chicken and egg problem. Q2 is off by default so what will turn it on? (SYS is also off!)
I suspect, you will need to power the CPU directly from the battery in order to do what you want, in which case, have a good power down mode.