BQ25710: Switching with audible noise

Hi, Leo,

It looks the board has some issues, the current spike is much higher than the other board. It pulled down the Vin, resulting in poor efficiency and audible noise. 

Please try ABA swap to see if a new IC fixes the issue or not. Otherwise, the board needs to be replaced. 

Regards,

Tiger

Hi Tiger,

I use normal's board, but there is the unstabel issue when VSYS with load. Could you help to check the waveforms?

And how to know the BQ25710 internal buck-booster is stable? thank you.

Load: 2.5A

Load: 0A

Hi Tiger,

Improved after adding input capacitance when buck mode. Thank you.

In addition, I connect the battery and during charging when the VSYS voltage is close to the VIN voltage, the BQ25710 will enter the boost mode, but the switching frequency of SW2 is not fixed. This seems to affect the current, as shown in the waveform below.

Is this normal? 

This is normal. It will seamlessly transition to buck-boost mode. 

Hi Tiger,

The following are the waveforms of different charging current settings(2A/2.5A/4A).

Why is the variation at 2A greater than other currents? Could the stability of the current be improved? Thank you.

You can try below compensation. 

Hi Tiger,

There is another phenomenon that needs to be asked.

When VSYS with 0.1A light load.  SW1 has double pulses. Could you please help to check the waveform? Can this be resolved?

Below are the waveforms of SW1 and SW2.

Below are the waveforms of SW1 and HIDRV1 and LODRV1.

Hi, Leo,

This is typical PFM waveform. When load increases, it transitions to PWM operation. 

Regards,

Tiger

Hi Tiger,

In the light load, there is audible noise and the current will become very unstable.