Application information

TSX711, TSX711A, TSX712

20/31

DocID025959 Rev 5

5.7

High values of input differential voltage

In a closed loop configuration, which represents the typical use of an op amp, the input

higher input differential values, such as:

operation in an output saturation state

operation at speeds higher than the device bandwidth, with output voltage dynamics

limited by slew rate.

use of the amplifier in a comparator configuration, hence in open loop

Use of the TSX711, TSX711A, or TSX712 in comparator configuration, especially

5.8

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 34: "Stability criteria with a serial resistor at different supply voltage" shows the

serial resistor that must be added to the output, to make a system stable. Figure 35: "Test

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

Figure 34: Stability criteria with a serial resistor at different supply voltage

100 p

1n

10 n

100 n

10

100

1000

Vcc=2.7V

Vcc=16V

Unstable

Stable

Vicm=Vcc/2

Rl=10k

Ω

Gain=1

T=25°C

Cload (F)