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# TL084H: In/Out limitation

Part Number: TL084H
Other Parts Discussed in Thread: TLV9001, TLV9051

Hi team,

When customer try the below non-inverting circuit, customer see non-linear in V_IN<0.3V. Vcc=5V, Vee=GND

If I understand correctly, Vcm should be 1.5V < Vcm < 5V from datasheet. Also Vcm = V_IN. I'm not sure why there is linear in <1.5V.

Also output voltage swing limitation is also violated since its head room exists.

What is the solution for this case? lets change opamp to rail-to-rail or Vee should be negative supplied, right?

Best regards,

Hayashi

• Yes. I'd guess that a rail-to-rail opamp like the TLV9051/TLV9001 would be simpler and cheaper than generating a negative supply.

• Hello Hayashi,

Either solution can help in this circuit. How close to 0V do you need the output to go. If you need the output to be 0, I would supply a negative voltage on the VEE pin.

If 5 to 10mV from the rail is ok, it is easier to switch to a TLV9001/TLV9051 device.

Best,
Jerry

• Hi Jerry, Clemens,

Thanks for the solution. But I don't understand theoritically still.

If I understand correctly, Vcm should be 1.5V < Vcm < 5V from datasheet. Also Vcm = V_IN. Why is there linear in <1.5V.

Regards,

Hayashi

• That 1.5 V value is the worst-case specification, so the typical behaviour will be better. Voltages above 1.5 V are guaranteed to be linear in all circumstances; there is no guarantee what happens below 1.5 V.

• Hayashi,

Over process and temperature variations, the non-linear behavior will start at different voltages. For robust performance, you should keep the input signal more than 1.5V above your negative rail.

Best,
Jerry