Connect to an external power supply of 15V and start the mainboard. The power consumption of the board is 141mA. Plug in an unfilled battery and use a multimeter to measure the changes in the high (3.3V) and low (0.019V) level of the BQ24133 STAT pin. It indicates that the battery is improperly charged.
So we do below test:
1. Test VISET voltage =0.133V> 0.12V, normal voltage; Test CHARGER_VREF_3.3V=3.293V,BQ24133 power supply voltage is normal,BQ24133 does not work because VISET is less than 0.12V or chip power supply voltage error is excluded
2.Confirm that the board power consumption current is 142mA not under 2.75A, the current is not over limit
3. Test BQ24133-Pin18 voltage, namely VOVPSET (#3) =1.390V, VOVPSET (#2) =1.372V, VOVPSET theoretical value =R607/ (R604//R97+R607) *AC-DC_PWR=1.388V, 0.5V< VOVPSET = 1.390/1.372 V< 1.6V Normal, the voltage is not over the limit;
4. test BQ24133-Pin10 voltage, namely VTS (#3) =2.072V, VTS (#2) =2.069V;
When the battery is absent, the theoretical value of VTS = (R612//R620)/(R612//R620+R610) *CHARGER_VREF_3.3V=1.109;
When the battery is in position (assume that the NTC resistance temperature is 25℃, RNTC=10K) Theoretical value of VTS = (R612//R620//RNTC)/(R612//R620//RNTC +R610) *CHARGER_VREF_3.3V=2.119V is close to 2.072V and 2.069V.The BQ24133 does not work because the battery temperature exceeds the limit or the battery is absent
5, test TP99 voltage (battery voltage detection circuit) is (#3) 2.547V, (#2) 2.349V, VTP99 theoretical value =VBAT* (R140/ (R140+R135)) =2.65,
When VBAT (#3) =12.27V, VTP99 (#3) should =2.583V; When VBAT (#2) =11.31V, VTP99 (#2) should =2.381V;
Considering the resistance error, 2.547V and 2.583V, 2.349V and 2.381V are close to each other, which can determine the battery position.
6.The board card is replaced with BQ24133, and the charge is normal after being powered on.
Below is sch: