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TPS54550 Disable low level input voltage test in datasheet.

Donald Nye
Prodigy 10 points
Other Parts Discussed in Thread: TPS54550

The stated max value for this test on page 5 of the datasheet is 0.5v.   When I do this test I get about 0.8v.  Can you tell me the proper way to perform this test to get a typical value? The data sheet says that if an application requires the TPS54550 to be disabled then use open drain or open collector output logic to interface with the SSENA pin.  Can you tell me why this is necessary?  If I just use a regular voltage source will this cause the disable low level input voltage to be affected?

Thanks

  • 0
    TI__Guru**** 191445 points

    I checked this on the EVM, both with and without Css cap.  Since SS/ENA is a dual function pin, it is difficult to resolve when driving with an external voltage.  The apparent EN threshold is 0.8x V,  but it may be possible that the device is enabled at less than 0.5 V but the ENA/SS  voltage is commanding a zero duty cycle (non switching condition).  Bottom line is that it is difficult to measure the EN threshold in a closed loop system.  Why is this an issue for you?