LMV341: Can I use this Amp for voltage follower circuit ?

user803165

Part Number: LMV341

Hi,

I want to use this amplifier for the voltage follower circuit.

However, when I simulate the circuit, the gain characteristic seems to be unstable with capacitive load (0.2uF or so).

As a common countermeasure, there is a method of connecting a series resistor to the output terminal (outside the loop) of the amplifier, but is there a disadvantage of this method?

Please tell me how to use this amplifier stably as a voltage follower circuit.

over 6 years ago

0 Ron Michallick over 6 years ago

TI__Guru*** 140026 points

User,

Yes, a outside the loop resistor helps.

Final output voltage can drop with output current VOUT = VIN - R * IOUT

Two resistors and a capacitor solution solves that problem.

Here is a circuit to test. Phase margin = 87 degrees

LMV431,2 Cap Drive.TSC

0 user803165 over 6 years ago

Prodigy 20 points

Hi, Ron
Thank you for your help.

But I can not understand part of this circuit.

- How does L1 (1kH?) Work?
- What is "B" in the circuit?

Regards,
Makoto

0 Ron Michallick over 6 years ago in reply to user803165

TI__Guru*** 140026 points

L1 and C3 create a DC operating point for the op amp. L1 and C3 are large enough thet for any practical frequency the feedback path is open loop. Therefore a AC transfer function at "B" (just a letter I picked) will show the loop bandwidth, gain and phase margins.

Normal usage after checking stability is complete will be to make L1 and C3 zero (remove them)

Unground non-inverting input and connect your input voltage.

It is OK to make supplies single supply.

Amplifiers

Amplifiers forum

LMV341: Can I use this Amp for voltage follower circuit ?