BQ51013C: adaptive communication limit

Hi Hanno

Adaptive communications will limit changes in output current during communications time.  This could cause a drop in output voltage during communication time.  

The feature will help maintain communications with a noise load.  

Hi Bill,

I observed that when the adaptive communication limit is enabled, wireless charging stops after a short duration, typically between 40 ms and 90 ms. However, when I disable this feature, charging proceeds without any issues.

Based on your explanation, I would expect the adaptive communication limit to restrict the output current, but not to terminate charging entirely.

Thank you.

Hi Joao

João Rego said:

Based on your explanation, I would expect the adaptive communication limit to restrict the output current, but not to terminate charging entirely.

During Adaptive communications the output current is limited, and output voltage will drop.  If the voltage drops far enough the unit will restart. 

Check Vout and RECT during communication with adaptive communications enabled.

But is unit is working better without it then this would be the better solution.

Hi Bill,

Could you clarify what you mean by "voltage drops far enough"? As shown in the images below, the unit shuts down with an output voltage of 4.8V.

The unit seems to perform better without it, but I would prefer to prioritize wired power over wireless (EN1 and EN2 = 0).

Also, in the past, I have had a problem with the BQ51013CEVM, where I had a voltage drop at the output. The impact on the output current was a voltage drop followed by an overshoot. In this previous issue, the unit never shut down. You can see more information here: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1453860/bq51013cevm-5v-output-voltage-drop/5625687#5625687

Thank you.

Hi Joao

The voltage drop does not look like the output or RECT going undervoltage and triggering a reset.  The reset is occurring after the communications packet this could be due to overshoot on output, or end power transfer command.  

During power transfer the control error packet is set every 250ms, only need one good packet every 1.5 seconds.

For large output error the control error packet is sent every 30ms, this looks like what may be happening.

Hi Bill,

I agree that a large output error might be occurring, as I already received the error after 90ms. Do you have any idea how I can check what kind of error I have?

Thank you.

Hi Joao

I will contact you by PM.