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SN74AHCT541: SN74AHCT541PW output incorrect voltage

Part Number: SN74AHCT541

Hi Guys

could you help review our schematic below? A1-A8 are digital signal from MCU. These are PWM signal. The Y1-Y8 are PWM output to IPM driver signal. three pahse full bridge IPM.

During the test, we found that when the high-voltage DC bus is frequently powered on and off, one of SN74 devices shows that Y4 (15pin) can only output 4V PWM waves, the others are normal 5V; Please help us analyze the cause of this failure. I doubt these device is damaged by the couple high voltage signal. Could you review this schematic firstly?



  • Hi Pengfei,

    I don't see any problem with the schematic as shown, however I can't see the load connected to the SN74AHCT541.

    Does this issue recover after another power cycle, or is it permanent?

    Can you provide scope shots of normal operation and the failure?