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ULQ2003A: TPLH about 10 times longer than TPHL

Howard Zou
Genius 12365 points
Part Number: ULQ2003A

Hi, 

we test this device finding that TPHL=30ns, TPLH=300ns.

But the typical value of TPHL and TPLH are the same in datasheet.

I wonder if what we observed is normal.

What's our test condition for TPHL and TPLH? Is Figure 18 the test circuit?

Personally I think TPLH should be related to external pullup resistor value, larger pullup resistor will result in longer TPLH, right?

  • 0
    TI__Genius 13760 points

    Hi Howard,

    Welcome to E2E!

    You are exactly right. The TPLH spec in the datasheet is the devices behavior under no loading conditions. Once the device has been disabled the output will no longer depend on the device, but on the components on the output. A larger resistor will result on a longer TPLH, but it will also be affected by the rest of the circuitry on the output. The output signal when disabled will be independent of the ULQ2003A device, so the customer will have to design according to their requirements.

    Best regards,

    Andy Robles

  • 0 in reply to Andy Robles
    TI__Genius 12365 points

    Sorry what do you mean by "disable" here, no enable or disable pin for the device.

  • 0 in reply to Howard Zou
    TI__Genius 13760 points

    Hi Howard,

    By disable in mean when the input of the device is driven low, shutting down the BJT's in the device.

    Best regards,

    Andy Robles