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LM5169-Q1: LM5169

Tony Nohra
Prodigy 20 points
Part Number: LM5169-Q1
Other Parts Discussed in Thread: LM5169

Hello,

We're planning on using the Power-good indicator pin on the LM5169 to trigger a backup PS once the Input Voltage VIN drops below 6V during a transient test.

What is the PGOOD COMPARATOR operating range? Would the PGOOD flag pin continues to operate if VIN Voltage drops down to 3.5V?

Thank you,

Tony

  • 0
    TI__Genius 12475 points

    Hi Tony,

    Thank you for your question. According to the datasheet it looks like the maximum ratings of the PGOOD pin is from -0.3 to 14 V. Once the FB voltage falls below 90% of Vref, an internal PGOOD swithc will turn on and pull PGOOD low. This will happen way before VIN drops to 3.5 V. More information can be found in section 8.3.9 of the datasheet. I have included it for your convenience:

    Please let me know if you have any other questions,

    Joshua Austria

  • 0 in reply to Joshua Austria
    Prodigy 20 points

    Hi Joshua,

    The Power-good indicator pin will be pulled up to 12V.

    What would happen if VIN dropped to 3.5V and stayed at 3.5V for 5 seconds?

    Would the PGOOD COMPARATOR be able to keep PGOOD Pin low and the FET switched ON for 5 seconds at VIN=3.5?

    What is the PGOOD COMPARATOR VCC source?

    Can the PGOOD COMPARATOR operates down to VIN=3.5V?

    Thank you,

    Tony

  • 0 in reply to Tony Nohra
    TI__Genius 12475 points

    Hi Tony,

    Thank you for your questions. PGOOD will stay low until the FB voltage rises to above 95% of Vref. It has a built in glitch delay of 5 us for the rising edge of PGOOD.

    Yes the PGOOD pin should be able to operate down to 3.5 V.

    Thank you,

    Joshua Austria