BQ25882: question about BQ25882

Hi,

What type of VBUS surge test are you doing? Do you have more details about the VBUS surge?

Thanks,

Ning.

Hi Ning：

Surge instrument coupling method: capacitor/inductor

Problem phenomenon:
Connect the low-voltage surge instrument and select capacitor/capacitor mode. The machine does not charge

Preliminary analysis:
1. Same environment, same surge instrument, machine (different charging IC); Using TI charging chips, the machine cannot be charged, whereas using SGM charging ICs, the machine can be charged
2. Even if the OVP is removed from the board, it cannot be charged. Check if it is caused by overvoltage protection of the OVP
3. From the waveform comparison, the difference in SW switching frequency causes the instrument capacitance to instantly drop within 3V, resulting in inability to charge
Please help confirm. thank you!

The following waveform:
Surge instrument input terminal (probe 1), surge instrument output terminal (probe 2), charging IC-SW signal (probe 3)

The following is the enlarged image of the above picture

The comparison waveform of SGM charging IC with competitors is as follows:

Hi,

We will check and get back to you.

Thanks,

Ning.

Hi,

Referring to 8.3.3.1 Poor Source Qualification on the d/s, If a poor source is detected (condition 2 above), the device repeats poor source qualification routine every 2 seconds. After 7 consecutive failures, the device sets EN_HIZ = 1, and goes to HIZ mode. The battery powers up the system when the device is in HIZ. Adapter re-plugin and/or EN_HIZ bit toggle is required to restart device operation. The EN_HIZ bit is cleared automatically when the adapter is plugged in. Is this what you observed?

Thanks,

Ning.

Hi Ning,

The key thing we observed is the VBUS drop quickly from 5V to 3V in 50uS even we set the VINDPM to 4.4V, could you advise the response/loop time of VINDPM?

Hi Ning,

Thanks for your info. Actually it has pass poor source detection and start fast charging, as you can see from below waveform(CH2: 5V BUS,CH3: SW). BTW, What is the soft start time of BQ25882?

Hi,

We are checking and will get back to you.

Thanks,

Ning

Hi Mike,

the product is mobile POS, and can't disconnect the SYS load.

Hi Mike,

the end product is mobile POS, and the SYS has battery power even the adaptor doesn't plug in. Besides, it is multi-layer pcb and we can't remove SYS load, we have removed the LCD display, the SYS is around 100mA now. the SYS always has power( 8V, same as battery voltage), the challenge is VINDPM doesn't work and drop to 3V even we set VINDPM to 4.6V, kindly need your suggest.