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SN65HVD888: How to test VOL and VOH?

Stanley Xu
Intellectual 1810 points
Part Number: SN65HVD888

Hi colleagues,

Customer want test and verify  VOH and VOL of SN65HVD888, can you show me the specific test circuit for these two parameter?

how to set the Peripheral circuit and adjust IOL(8mA or -8mA as show in DS)?

  • +1
    Guru 316440 points

    This is a plain CMOS output, so nothing special is required.

    Connect a 8 mA current/source between the output and GND/VCC, and measure the voltage. Alternatively, connect an ampere meter in series with a voltage source, and adjust the voltage source until you get 8 mA.

    If you just want to check that the device meets the datasheet specifications, connect a 325 Ω resistor to GND or a 575 Ω resistor to 5 V (these result in an 8 mA load at the specified limits), and measure the voltage.

  • 0
    TI__Guru 52022 points

    Hi Stanley,

    Clemens is correct - either way mentioned is fine to measure the output voltage levels. If you have any other questions please let me know!

    Best,

    Parker Dodson

  • 0 in reply to Clemens Ladisch
    TI__Intellectual 1810 points

    Hi Clemens, customer said when they test this 888 device whatever they put +200mV or  -200mV at AB, the R always output high level, is the non-polarity feature cause that? and how can we modify the test circuit 

  • +1 in reply to Stanley Xu
    Guru 316440 points

    Yes; the bus-polarity correction feature assumes that an idle bus is high.

    To make the receiver switch low, you must input pulses shorter than tFS (44 ms).

  • 0 in reply to Clemens Ladisch
    TI__Guru 52022 points

    Hi Stanley,

    Clemens is correct here as well. 

    Please see highlighted line in datasheet excerpt below for polarity correction conditions:

    As a note - this device is only setup to work with fail-safe resistors - if these are not included device behavior may not be consistent with expected results. 

    Best,

    Parker Dodson