BQ25101: BQ25101: /CHG keeps low sometimes in UVLO condition.

Hello Sasuke,

Can can attach the schematic and any waveforms you have showing the issue.

Thanks,

Nick

"To post on TI E2E design support forums, you must have a valid company email address in your myTI account" - what i see when i reply, unfortunately. 

There is VIN connected to 3.0V system and rises to 5V when charging is enabled. 3.0V comes from LDO that comes from VBAT(VOUT of BQ25101). So VOUT can vary 3.2 to 4.2 battery voltage. VIN can vary 2.8 to 5V. In my case 30 samples of this charging module and 10 of them stays LED indicated after power on (CHG is low). Whenever all BQs able to charge. Other 20 works as expected. Power switch is mechanical and between VBAT and LDO 3V0. Can it be factory issue (30% is lose is too bad) or the unclear function of BQ25101?

This is power on Transient Voltage. Blue - VBAT(Vout), Green - 3V rail, Yellow - Vin ( = 3V - diode drop)

Thank you for reply. So you recommend to lower the Vin (<2V may be) to complete shutdown the BQ. Or Vout must be somehow separated?

Hello,

In my testing I saw /CHG stay low down to around 3V on Vin, so 2V may be a good value to use here.

BR,

Nick

OK. In out project we proceeded from datasheet Section 7.5, that UVLO is 3.15 and greater. so we designed to 3V. Now as i understand the datasheet can be unclear or the MIN MAX values can be wrong, so we have to change our PCB/Production state, or just throw away a 30% of chips to get a normal operation. Kinda sad(

Is it possible to increase UVLO detection voltage, f.e. 3.6-3.8 Volts? 

8.4.1 Power-Down or Undervoltage Lockout (UVLO)

The bq2510x family is in power down mode if the IN pin voltage is less than UVLO. The part is considered “dead” and all the pins are high impedance. Once the IN voltage rises above the UVLO threshold the IC will enter Sleep Mode or Active mode depending on the OUT pin (battery) voltage.

OK. But how about this? Do you think it is ok?