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Amplify switching signal by THS3125

Nick Dai
Expert 4240 points
Other Parts Discussed in Thread: THS3125

Hi Team,

   The customer use below schematics to amplify a swithcing signal to get a better rising and falling edge,but the found some THS3125 output incorrect signal.

The input signal is a 3.3V switching signal,VCC+=5.4V and VCC-=-15V.

For normal device,the high level of output is about 4v to 4.5V,and the voltage will not change when the output current is about 30mA(Yellow is input,blue is output)

For abnormal device,the high level of output is about 3.8V and there is more then 0.1V different beween VIN+ abdVIN-.Th high level output will decrease to 2.2V to 2.7V when tht ouput current is 30mA.

Could you help review the schematic at first and then check why the abnormal device can't output correct voltage? And is there any way to optimize this circuit?

Best Regards,

Nick Dai

  • 0
    TI__Genius 13935 points
    Hi Nick,

    I posted a reply, but it disappeared.

    Can the customer use a higher voltage power supply on Vcc+? If you can have a +10V power supply it should fix this.

    If you look on page 6 of the datasheet you can see that between 2V and 1V from the supply rail is the expected voltage swing, depending on load and output current. It looks like normal process variation is giving some parts with weak output swing.

    Regards,
    Loren
  • 0 in reply to Loren Siebert 1
    TI__Expert 4240 points

    Hi Loren,

      Thanks for your feedback.

      i have asked customer to try to improve the positive power supply voltage.

    Best Regards,

    Nick Dai