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TPS92691EVM-752: TPS92691-Q1 output short circuit question

Kuo Duke
Expert 2040 points
Part Number: TPS92691EVM-752
Other Parts Discussed in Thread: TPS92691, , TPS92692

Hello team,

May I know TPS92691 have output short circuit protection? and how to implement the protection?
Since we dircet short output test on TPS92691EVM-752 and find DDRV pin voltage level from 7.5V change to 5.4V cause Q1 FET not turn off.

  • 0
    TI__Intellectual 2580 points

    Output short protection is possible by using the IMON current monitor pin.  If the current is in regulation V(IMON) = V(IADJ).   In the event of a short the LED current will be above regulation, therefore V(IMON) > V(IADJ).   The customer can take the IMON voltage and connect it to an ADC input of a microcontroller to determine when it is sufficiently above regulation. Then, when it is too high, the microcontroller can short SS to GND to disable the GATE output.

    If the customer does not have a microcontroller in the system, they could use a comparator, a reference, and several transistors to do the same thing with less flexibility of course.

    There is also the TPS92692 which has all the same features as the TPS92691, but adds an open drain fault output that will automatically pull low when the current is 50% above regulation [ V(IADJ)= 1.5*V(IMON) ].  If the FLT pin is tied to SS, then the GATE shutoff will be automatic in that case.  Please review the TPS92692 datasheet if you are interested in this feature.

    -JP