Part Number: TDA4VM-Q1
Other Parts Discussed in Thread: TDA4VM
Hi TI:
When the TDA4VM is loaded TIDL or booted, some PCBAs will report a POK fault, which will cause the board to restart due to the corresponding VDD_CPU_OVERVOLT.
Current VDD_CPU Overvoltage and undervoltage threshold setting: 0.6V-0.9V.
We tested the voltage of the VDD_CPU circuit:
Maximum voltage during normal operation: 854mV.
When we started running the TIDL model, we noticed an increase in ripple, and the maximum value we caught was 896mV, which is close to the overvoltage alarm threshold.
We tried to make the following change tests:
1. Increase capacitance at the voltage output and SOC pins; No improvement was demonstrated.
2. Adjust the PMIC to forced PWM mode and multiphase mode; Proven improvements, the probability of recurrence will decrease, but it will still recur.
3. The FB feedback trace is the remote feedback, and the line is routed according to the trend of the power supply copper pour, accompanied by the ground wire. And the external coaxial feedback line was tested and there was no improvement.
4. Use an oscilloscope to measure the highest level of the power supply, the highest level is 897mV, and the CPU overvoltage threshold is set to 900mV. The threshold was not reached, but a fault was reported.
5. For different chips, the CPU voltage of the chip is high (average voltage: 0.85V), and the CPU voltage of the normal chip is near the typical value (average voltage: 0.8V).
6. Modify the POK overvoltage threshold test, modify it to 0.9125V and no longer reproduce.
Please ask:
1] The actual measured CPU peak voltage does not reach 900mV (the set overvoltage threshold is 900mV), but the POK reports an overvoltage fault, what is the reason?
2] Check the default setting of the CPU POK in the TI SDK The overvoltage and undervoltage threshold is 0.725V-0.8625V, but the TDA4 manual clearly describes that the setting range of CPU AVS voltage is 0.6V-0.9V; if it is set according to the default value, the voltage of some chips in the normal state will exceed the overvoltage and undervoltage threshold range, what are the settings of the default value in the SDK?
3] The over-under-voltage range of the POK CPU we currently set is 0.6V-0.9V, which refers to the maximum and minimum value of this power supply (0.6-0.9V) in the manual？
4] If you need to expand the threshold range, how much is it appropriate to expand it, is it appropriate to follow the 9% setting ([0.6*9%, 0.9*(1+9%)]), or is there any recommendation?
Thanks！！
