I'm attempting to validate my charger design using BQ24072T and having issues, not seeing any charging current.
My battery is a 1S4P, 3.7V nominal. For the test, I've discharged it to approximately 3.5V.
For the test, I keep EN1 and EN2 low to attempt 100mA charging.
My charger input is 5.0V DC. When I apply the 5V source, I can confirm that PGOOD pulls low as expected.
I then probe around the circuit:
Vbat = 3.54V.
Vin = 4.994V
Vout = 3.74V
I then set CHG_CE low and probe CHG, and can confirm that it has pulled low and remains low which should indicate that the device believes it is charging.
I have a DMM in series with my battery to monitor battery current, and see none.
I then probe the voltage at Iset (which per the datasheet, the current out of Iset should reflect 1/400 of the actual charging current). My Rset resistor is 590ohms, and I measure 0.0V on the Iset pin of the charging circuit. This agrees with my external DMM - the charger IC appears to be telling me with the CHG signal that it is indeed charging, but no charge current is present.
I have also attempted trying different combinations of EN1 and EN2, but see no changes with any EN1/EN2 configuration.
I'd like to confirm the package markings here to make sure it's the right component, but cannot find package markings in the documentation.
My IC package shows 3 lines of text:
PAP
TI 878
A1PQ
I'll add some other configuration notes at the end here:
My Ilim is set to 1.5A with a 1.07k resistor, TD is connected to GND, and Rtmr = 72k
Questions:
Are there any other suggestions for what to check here to determine why the charger is not actually providing current?
Are these package markings for the BQ24072T correct?
Is my battery voltage not low enough to actually trigger charging, and if not, why is the charger indicating that it is actually charging with the CHG signal?
I've also just noticed datasheet section 9.3.12 Temperature Monitoring - my current battery pack does not have an NTC and I simply have a 10k resistor to GND attached to the TS input.
I see now for applications which do not require TS monitoring that it should be a divider which sets the TS input voltage to between Vcold and Vhot.
Does it seem like the low TS voltage could be the culprit here?
Thanks!