• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 726 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UC2903: Response time to a UV/OV fault.

Edward Jung65
Prodigy 40 points

Part Number: UC2903

I would like to use the UC2903 in an ultra-fast protection circuit.  How fast can the UC2903 respond to a OV/UV fault with no external fault-delay capacitance at pins 10 and 13?  The data sheet doesn't specify the propagation delay.   

  • 0
    TI__Genius 12630 points

    Edward,

    This data isn't provided in the datasheet but I think we can come up with an approximation. It will depend on the pin (and trace) capacitance once the device is in circuit but let's assume ~270pF (this is the minimum external capacitance allowed according to the typical characteristics curve on page 5).

    And we know the Charging current (60uA) and the threshold voltage (1.8V) from the EC table on page 3.

    Using I = C dv/dt and solving for dt gives about 8us. This approximation is close to what I would expect for a voltage detector prop delay with no external delay. I would guess the delay might be as high as 50us. The best way to find out is to test the device in your circuit and measure the delay.

    If you would like to see our newer over/under voltage detectors, check out TPS3700 (18Vin max & adjustable thresholds), TPS3701 (36Vin max & adjustable thresholds), and TPS3702 (18Vin max & fixed thresholds). These datasheets have much better timing information.

    I hope this helps! Please click “This resolved my issue” button if the answer provided resolved your issue.

    -Michael