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LM20333: Undervoltage Comparator

hideyuki sakai
Mastermind 6250 points
Part Number: LM20333

Dear, Sir.

My customer is looking for the device to protect against abnormal FB voltage due to

external FB resistor divider open or short.

LM20333 looks have the internal undervoltage comparator inside of FB path.

Could you explain the behavior about the undervoltage protection if it had certainly.

Is it similar as OVP? Please give your advice.

Best Regards,

H. Sakai

  • 0
    TI__Mastermind 25590 points

    H. Sakai,

    Pg 11 of the datasheet explains these comparators:

    "The LM20333 has built in under and over voltage comparators that control the power switches. Whenever there is an excursion in output voltage above the set OVP threshold, the part will terminate the present on-pulse, turnon the low-side FET, and pull the PGOOD pin low. The low-side FET will remain on until either the FB voltage falls back into regulation or the negative current limit is triggered which in turn tri-states the FETs. If the output reaches the UVP threshold the part will continue switching and the PGOOD pin will be deasserted and go low. Typical values for the PGOOD resistor are on the order of 100 kΩ or less. To avoid false tripping during transient glitches the PGOOD pin has 20 µs of built in deglitch time to both rising and falling edges."

    -Sam