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THS6182 never OFF

audic mickael
Prodigy 10 points
Other Parts Discussed in Thread: THS6182

We are using THS6182.

As you can see on the schematic, the THS6182 is powered in +- 12V and Bias2 is always to 3v.

When we put Bias1 to 0v, amplifier is ON, in low bias mode (cf datasheet).

But, when we put Bias1 to 3.2v, the amplifier is still running instead of sleep mode.

 In the screenshot below : pink is Vin1 and blue is gate Q3, with THS6182_ON/ = 3.2V

Do you have any idea of what can happened?

Thanks and regards,

Mickael

  • 0
    TI__Genius 13335 points

    Hi Mickael,

    The first thing I notice is that there is a voltage divider connected to Bias2. This would drop the voltage at the pin from 3.3V to 2.7V. From the datasheet, the threshold voltage for both Bias-1 and Bias-2 to be on is 3.3V. I would try replacing R226 with a short and verify that there is 3.3V on both Bias-2 and Bias-1 for the proper shutdown condition.

    Let me know if this fixes the problem.

    Regards,
    Luke

  • 0
    Prodigy 100 points

     Hi Mickael!

    The THS6182 worked properly, but U12B (inversion stage) will transmit the signal through R50 and R53  to output. All wery simply.