BQ25792: What is the minimum current it supplies without battery for 2S setting as well as it Emits noise when charging is in progress.

Hi Burhanuddin,

I don't see any obvious issues with the schematic. The 47nF on BATP is not needed but should not cause a problem.

Without a battery and with charge enabled, BQ25792's converter shuts down for 30ms due to BATOVP.  You can prevent the BATOVP by disabling charge (CE bit or pin or TS fault) when no battery is attached or adding 200uF capacitor on BAT pin.  Or you can change to pin 2 pin and register 2 register BQ25798 which does not have the 30ms converter shut down.

Regards,

Jeff

Hi Jeff

Adding 200uF on BAT pin didn't resolve the issue, the charger is unable to provide power to the system when high current requirement is there, the system voltage resets when higher current is drawn from it.

In addition to this the charger status LED is not working.

What about the noise part? the same battery charges perfectly without noise from the EVB.

Hi,

What do the charger's status and fault registers report?  With 5V/3A from PD controller, the charger should be able to provide 15W/7Vminsys >2A at SYS.

If the charger's SYS is falling/rising at a frequency in the audible range, the output capacitors resonant.  Can you look at VBUS, VSYS, VBAT on a scope?

Regards,

Jeff

Hi Jeff,

When I added 200uF on Vsys the noise vanished and Adding 320uF on BAT pin resolved the resetting of system.

I am using around 50uF of ceramic capacitance at Vsys which is same as what is on the EVB, but in EVB there is no noise. what could be the reason

The capacitor package is 1206 and PN is CL31B106KBHNNNE. 

Hi Burhanuddin,

I need the scope plots before you added the capacitance to further diagnose the issue.  How close are the capacitors on your board to the IC?  Did you follow the recommended layout per the datasheet below:

Regards,

Jeff

The caps are very close to the IC, its almost same as the recommendation provided in the datasheet.

Here is the actual system image for your reference.

Hi Burhanuddin,

The layout looks reasonable.  In order to help further, I need the

-scope shots mentioned above 

-register dump of REG0x1B  through REG0x27

both with and without the extra cap.

Regards,

Jeff

Register Dump from 0x1B to 0x27 without Capacitor

1. Without Charging :  2F, 2A, 0, 50, 0, 0, 0, 80, 82, 10, 10, 20, 0

3. With Charging : 2F, 6A, 1, 40, 0, 0, 0, 80, 80, 0, 0, 20, 0

Scope shot without Cap

Register Dump from 0x1B to 0x27 with Capacitor

1. Without Charging :  2F, 2A, 0, 50, 0, 0, 0, 0, 82, 10, 10, 20, 40

3. With Charging : 2F, 8A, 1, 40, 0, 0, 0, 0, 0, 0, 0, 0, 0

Scope shot with Cap

This scope shot is of vsys without battery and with caps

Hi Burhanuddin,

The last plot is either when battery is attached or the pack protector has opened.  The charger hits BATOVP, converter turns off for 30ms, charge restarts, hits OVP, repeat.  Adding fixes this issue.  Or you can change to pin 2 pin BQ25798 which stills has the OVP event but converter does not turn off. 

The registers are report charging for both plots:

trickle charge with BATOVP sometime in the past

fast charge with BATOVP sometime in the past.

Could the pack protector OVP threshold be lower the charger VREG setting?

Regards,

Jeff