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TPS54040A: PWRGD Comperator Output Voltage

Thomas Schabel
Prodigy 10 points
Part Number: TPS54040A
Other Parts Discussed in Thread: NE555

Hi. In DS I found only on-resistance for PWRGD with 50R (typ) if active. But due to open drain output  I guess there is still a min voltage level on output if PWRGD asserts to low.

My application runs with 24V Vin, 5V Vout, ca 100mA out,  -25...+85°C. PWRGD will connect to NE555 timer on Reset pin that needs <= 0.3V to activate Reset in worst-case szenario.

Does anyone knows if I can use only 50R on PWRGD output to calculate level or are there any other limitations?

Thx & KR Tom

  • +1
    TI__Expert 5250 points

    Hi,

    As long as there is a pull up resistor between the values of 10k and 100kΩ to a voltage source that is 5.5 V or less, the voltage on PG pin when the internal FET is on can be calculated as: 50ohm/(50ohm+pull up resistor)*Vsupply. If pull up resistor is 10kohm and Vsupply=5.5V, Vpg=2.7mV, which is well below 0.3V.

    Regards,

    Hongjia