Application information

TSB572

20/27

DocID028308 Rev 2

4.6

Capacitive load

Driving large capacitive loads can cause stability problems. Increasing the load

capacitance produces gain peaking in the frequency response, with overshoot and ringing

in the step response. It is usually considered that with a gain peaking higher than 2.3 dB an

op amp might become unstable.

Generally, unity gain configuration is the worst situation for stability and the ability to drive

large capacitive loads.

Figure 36: "Stability criteria with a serial resistor at different supply voltages" shows the

serial resistor that must be added to the output, to make a system stable. Figure 37: "Test

configuration for Riso" shows the test configuration using an isolation resistor, Riso.

Figure 36: Stability criteria with a serial resistor at different supply voltages

Figure 37: Test configuration for Riso

+

-

VCC+

Riso

10 kΩ

VCC-

VOUT