BQ24192: bq24192 output is 4.125A, The temperature of bq24192 case is 107.5ﾟC bq24192 output have voltage drop.

Hey Bogey,

The BQ24192 has a thermal regulation feature that pulls back on charge current when the junction temperature of the IC is too high. This is normal when a battery is connected as the battery will eventually support the load/output. 

When there is no battery present, the output voltage regulation is allowed to fall to support the thermal regulation power reduction, and there is no battery to catch to falling output voltage. 

The thermal regulation point is 120C junction temperature, which is extremely likely if you are already seeing 107C on the case.

Based on your schematic, there is nothing I can see immediately that would warrant concern. I would also say that thermal issues such as this can be generated from a number of reasons. So I would urge to check and consider a few things: well soldered, via'ed, and dissipative thermal pad for the IC, sufficient power and ground copper pours for head dissipation, thermal vias under thermal pad of IC, system inside an enclosure or another area with poor airflow, radiant and self-heating from other components, especially inductors with high DCR and poor thermal conduction and diodes, possible shorts, and highly resistive paths carrying large amounts of current.

Regards,

Joel H

Hi Joel

If we use bq241992 in 107ﾟC and have battery pack, the system load will be switch to battery by bq24192,

The battery path can always keep when over junction temperature ??  Or will junction protect ??

                                                                                                               Bogey

Hey Dan,

The BQ24192 cannot reduce discharge current from the battery to the SYS load. There is only a MOS switch between BAT and SYS pins of the charger, so any attempt to reduce load to improve thermal loss will have to come from external control of the load.

The BQ24192 can only reduce charging current into the battery when an adapter is present when the junction temperature exceeds 120C. 

And you are correct, with both an adapter present and a battery pack at 107C_case, there is a strong likelihood that the charge current will reduce to 0 and the battery will supplement the system load.

Ideally, the thermal regulation is attempting to reduce the power loss through the IC's converter and by direct result, the inductor, but if junction temperature is already around this temperature, there is no way the thermal regulation can do anything to reduce that. 

One question is why your system environment is so hot @ 107C? 

Regards,

Joel H