TSX7191, TSX7191A

Application information

DocID026747 Rev 3

19/25

4.8

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

large capacitive loads.

Figure 31 shows the serial resistor that must be added to the output, to make a system

stable. Figure 32 shows the test configuration using an isolation resistor, Riso.

Figure 31: Stability criteria with a serial resistor at different supply voltages

Figure 32: Test configuration for Riso

100k

11k

Vcc+

Vin

Vcc-

Riso

Cl

10k

Vout

Ω

Ω

Ω