MP2762 read battery voltage when no vin available

Battery Management
1

Hello folks,

I am using MP2762A in a new application and so far everything seems fine.
I just noticed that I can’t read battery voltage (also current) when Vin is not available (no charge ongoing) unless I set OTG mode.

However when using OTG mode i loose charging capabilities (which is logical).

Is there any way to read out battery voltage when there is no VIN available?

Regards
Davide

2

Hello @vt100,

When Vin is absent, the MP2762A powers the system from the battery through the
integrated BATTFET (Q7). When the input is absent and OTG mode is
disabled, the part is set to Battery-Only mode and I believe you can read the battery voltage via REG16~17H register in the IC.

I hope this would help.

Best,
Saquib

3

Hello @Saquib.FAE

Thanks for your reply.
Unfortunately i just tested and R16~17H are read as 0 when Vin is absent, same consideration is valid for R18~19H.
I can hereby confirm that Vsys is available.
I tested with the evaluation board and as you can see from the picture below, the same behavior is observed.

image
image1020×604 34 KB

Regards
Davide

4

Hello again @Saquib.FAE

Seems the issue is related to register R0Bh, if it’s not set that PROCHOT and PSYS are enabled you can’t see bt voltage.

Regards
Davide

1 Like
5

Hello @vt100 ,

That’s correct. ADC is active on battery only mode when you set the REG0BH bit[1:0] register to 10 or 11 and enable PROTHOT and PSYS.

Please let me know if this helps.

Best,
Saquib