BQ25622EVM: Abnormal waveform on V_SYS with BQ25622 EVM as CV mode

Kevin Chin

Prodigy 110 points

Part Number: BQ25622EVM
Other Parts Discussed in Thread: BQ25622

Hi Sir,

We found there is abnormal waveform at V_SYS terminal on EVM board.

The condition is when the charger enters to CV mode and loading current drawn (~160mA) at system side by dummy loader.

But the sympton cound be disappeared by incerasing VBUS level.

The setting we only set the ITERM to 20mA and other parameter follows default value.

Could you please let us know what's going on with the charger at this moment?　

Is the symptom your expectation?　

4 months ago

0 Kevin Chin 4 months ago

Prodigy 110 points

Hi Sir,

I found that this symptom is always happend when the charging current is decreased to around 60mA and having loading from system side at the same time.

0 Ning T 4 months ago in reply to Kevin Chin

TI__Guru 50901 points

Hi,

What are the charger operating conditions such as VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS for the waveforms?

Thanks,

Ning.

0 Kevin Chin 4 months ago in reply to Ning T

Prodigy 110 points

Hi Ning,

I use an external power supply as charger source at VBUS side (5V/2A) and also use an external power supply as battery source. The current value is negative, which means the current into the power supply (battery).

By increasing the voltage of power supply at battery side to observe the BQ25622 operating behavior, and we don't see this abnormal symptom during whole charging process without any current drawn at system side.

Once having current drawn via dummy loader at system side, this phenomenon was always happened as charging current smaller.

In additional, there is not helpful even we tried to adjust VINDPM, PFM_FWD_DIS or EN_TERM.

I upload the other waveform such as VBUS and IVBUS for your check as well. Can you reproduce this symptom from your side?