about OPA544 high capacitance load problem.

yang yuchang

Other Parts Discussed in Thread: OPA544

I use OPA544 in voltage follower, and I refer OPA544 datasheet P8 . Figure 5 (output series L/R network helps assure stability with very high capacitance loads) in circuit, but when CL>0.1uF,voltage follower still unstable. I need this voltage follower has 0.5A at least. What is the best solution??

over 10 years ago

0 Tim Green1 over 10 years ago

TI__Expert 6275 points

Tell us exactly what range of capacitive load (minimum capacitance to maximum capacitance) you are trying to drive on the output and we can recommend the best solution. Also what is Vin in amplitude and frequency range. When you stabilize am op amp circuit for cap load you will lose bandwidth. Depending upon what your input signal is you may need a different solution.

0 yang yuchang over 10 years ago in reply to Tim Green1

Prodigy 40 points

The output capacitance range is 0.01uF to 1uF.

Vin is 10Hz~100Hz square wave which amplitude is -5V~+5V.

0 Tim Green1 over 9 years ago in reply to yang yuchang

TI__Expert 6275 points

What are power supply voltages and what is desired rise and fall time of input square wave? Is the load a Piezo actuator or just a capacitor?

0 yang yuchang over 9 years ago in reply to Tim Green1

Prodigy 40 points

The power supply voltages are +15V ~ -15V, and rise and fall time both 10ns.

Load just a capacitor.

0 Tim Green1 over 9 years ago in reply to yang yuchang

TI__Expert 6275 points

See attached for analysis and recommended circuit. With any design there will be compromises. You will not achieve 10ns rise and fall times with these cap loads. Attached will give you tools to analyze your design compromises.

OPA544 Cap Drive.ppt

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about OPA544 high capacitance load problem.