If the input pin voltage exceeds the power supply by 0.5 V, the ESD diodes become conductive and excessive

current can flow through them. Without limitation this over current can damage the device.

In this case, it is important to limit the current to 10 mA, by adding resistance on the input pin, as described in

Figure 50. Input current limitation.

+

-

Vin

R

VCC+

VCC-

5.4

Rail-to-rail input/output

+ 0.1 V.

The operational amplifier output levels can go close to the rails: to a maximum of 40 mV above and below the rail

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

∆T

max

( ) V

(

)

–

T 25 °C

–

=

°C

Where T = -40 °C and 125 °C.

The TSZ18x datasheet maximum value is guaranteed by measurements on a representative sample size

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.

TSZ181, TSZ182

Rail-to-rail input/output

DS11863 - Rev 5

page 19/43