TSZ182 datasheet(22/39 Pages) STMICROELECTRONICS

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Application information

TSZ182

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DocID029836 Rev 1

5.5

Input offset voltage drift over temperature

The maximum input voltage drift variation over temperature is defined as the offset

variation related to the offset value measured at 25 °C. The operational amplifier is one of

the main circuits of the signal conditioning chain, and the amplifier input offset is a major

contributor to the chain accuracy. The signal chain accuracy at 25 °C can be compensated

during production at application level. The maximum input voltage drift over temperature

enables the system designer to anticipate the effect of temperature variations.

The maximum input voltage drift over temperature is computed using Equation 1.

Equation 1

Where T = -40 °C and 125 °C.

The TSZ182 datasheet maximum value is guaranteed by measurements on a

representative sample size ensuring a Cpk (process capability index) greater than 1.3.

5.6

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

large capacitive loads.

Figure 51: "Stability criteria with a serial resistor at VCC = 5 V", Figure 52: "Stability criteria

with a serial resistor at VCC = 3.3 V", and Figure 53: "Stability criteria with a serial resistor at

VCC = 2.2 V" show the serial resistors that must be added to the output, to make a system

stable. Figure 54: "Test configuration for Riso" shows the test configuration using an

isolation resistor, Riso.

Figure 51: Stability criteria with a serial resistor at VCC = 5 V

∆V

∆T

ma x

io T

io 25

–

25 °C

–

°C

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