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THS3091: alternate solution for THS3091

Danidu Dabare
Prodigy 110 points
Part Number: THS3091
Other Parts Discussed in Thread: TLV1872, LM6171

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Hi TI team,

I’m building a custom over-voltage protection (OVP) circuit for an AWG output (±10 V, 50 Ohm up to 500 MHz).
For external signals, I only need the OVP detection to work up to ~50 MHz

In my circuit, the BNC output voltage is sensed directly (no shunt resistor).
U7 (currently THS3091) buffers this voltage and drives two TLV1872 comparators that detect positive and negative thresholds. The outputs are OR’ed to generate a fault signal.

Since this amplifier is only used for OVP sensing - not precision measurement - I'm wondering if THS3091 is overkill.

What I need from the amplifier:

  • Ability to sense ±15 V signals up to ~50 MHz (what i'm planning to detect)

  • Lower cost than THS3091

    Could you recommend a more suitable TI amplifier for this sensing stage, or confirm whether THS3091 is appropriate?

Thanks!

  • +1
    TI__Mastermind 30170 points

    Hello Danidu,

      Thanks for the details and simulation! 

      The THS3091 would have been overkill if it was chosen for high output current at high bandwidth since you are driving a high impedance load (the TLV1872 comparators). However, if you care about slew rate at +/-15V up to 50MHz sinusoidal signal, you would need around 4710 V/µs. This is important depending on your tolerance on how fast you need to detect an overvoltage at the threshold limit set at your comparators since low slew rate will affect your response time. 

       Price-wise, I would try with LM6171 since it fits all your required specifications, and has a slew rate of 3600 V/µs. This should be enough for your specific application for sensing. 

    Best Regards,

    Sima 

  • 0 in reply to Sima Jalaleddine
    Prodigy 110 points

    Hello Sima,

    Thanks for helping me out. 
    I integrated the LM6171 in the simulation and it seems to be working for my application.

    Thanks!