BQ25798: It does not work,when the battery was dead and the sun was rising slowly.

Hi Xingjian,

With slowly rising sun, the charger's input crashes down below VINDPMmin=3.6V and then to poor source which forces EN_HIZ bit =1 for ~10mins.  Then it sets EN_HIZ=1 and tries again. Eventually, I expect it to power up after multiple retries. How long did you wait before replug?  Can you send scope shots of VBUS, SW1, SW2 and SYS during one of the retries?

Regards,

Jeff

HI Jeff

Replug about five hours later.

How EN_HIZ change the state after 10mins,which power source it uses,RGEN?

HI Jeff

Do you have BQ25798EVM?You can test it with solar panels, in BYPASS mode.This is bound to come up.

Best Regards,

HI Xingjian,

There is an internal power rail (not REGN) that is powered from diode OR of VBUS and VBAT if available. Is your VBAT configured for higher than 1S = 4.2V?  

regards,

Jeff

Hi Xingjian,

I'm not sure what you mean by Bypass mode.  BQ25798 does not have a bypass mode where VBUS is feed directly to VSYS=VBAT.

Regards,

Jeff

HI Jeff

What I mean is no ACFETs-RBFETs, vbus input only;

HI

The VBAT configuration is 4.2V.

The premise of the problem is that the battery is dead.

Hi Xingjian,

I haven't seen this before and have not had a customer complain.  If you can send me the waveforms previously requested, I can investigate further.

Regards,

Jeff