Solution: BQ24735RGRR has occasional abnormal power on problem
Fault symptom:
This fault is caused by occasional system power failure during normal use of the product. The problem may be resolved by shutting down and restarting, or the system may still not be able to power on when restarted;
By analyzing the faulty instrument, it was found that the fault was due to the inability of pins 3 and 4 of the BQ24735 chip to generate normal level conduction MOS, resulting in the system being unable to supply power;
The two instruments that had problems at the beginning of the test were all in the same condition. When the fault occurred, the voltage at pins 3 and 4 of BQ24735 chip was 0; During normal operation, the voltage is 12 and 18V, used to conduct two MOS。
Design:
Waveform of abnormal power on:
Waveform of abnormal power on:
Tested:
1. I have conducted ABA cross experiments before; Fault with the chip;
2. During testing, the display screen and other loads were not connected; Eliminate the issue of load overload;
3. There is a small probability of recurrence of restart failure phenomenon;
4. After looking at the waveform during power on, it was found that the voltage increased rapidly at the ms level during power on, and the voltage decreased slowly during power off
5. As can be seen from the waveform above, the two pins of the chip that works once cannot generate normal levels. They have been trying, but they have been unable to provide normal levels
At present, we are unable to confirm the cause of the problem. Please seek help to resolve it. Thank you!
