MC33772C voltage error

[kevinyuee]

Hi,
   What should be the default power-on state of MC33772C? My current power-on status is like this. Is this normal for the mc33772c? After I tried to cancel the mc33772c, the voltages collected at both ends of the collection points were consistent and normal.

Please reply asap to
Kevin

[JozefKozon]

Dear Kevin,

however with such high voltage difference, it looks more like some of the external components are damaged. Either a resistor or a PCB trace interrupted or short to the GND.

With Best Regards,

Jozef

[JozefKozon]

Dear Kevin,

the difference in the voltage between the channels can be because of active balancing. Please see below an answer to another customer experiencing voltage change (raise and drop) during one channel balancing. 

DESCRIPTION

This behavior is typical of a serial resistance in the cell terminals. If a load is applied on cell2 through the cell terminals (such as bell balancing for example), it will generate a voltage drop on the line. Since cell3 measurement utilizes the same cell terminal, the same drop will be observed on cell3, but on the opposite direction and typically half the magnitude.

If the load is applied to the whole battery pack (via the power negative and positive battery terminals), you should not observe this behavior.

In a nutshell, to avoid this behavior, either reduce cell terminal resistance or reduce the load current.

With Best Regards, 

Jozef

[kevinyuee · Accepted solution]

The problem was solved after the reference GND and the chip GND were short connected.