Common Mode Voltage (V)

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SNOS

IQ (nA) at 125 °C

IQ (nA) at 25 °C

IQ (nA) at -40 °C

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TLV8544, TLV8542, TLV8541

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SNOSD29E – DECEMBER 2016 – REVISED APRIL 2018

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Device Functional Modes (continued)

Figure 30. Supply Current Change Over Common Mode at 1.8 V

For the lowest supply current operation, keep the input common mode range between V– and 1 V below V+.

8.4.3 Design Optimization With Rail-To-Rail Input

In most applications, operation is within the range of only one differential pair. However, some applications can

subject the amplifier to a common-mode signal in the transition region. Under this condition, the inherent

mismatch between the two differential pairs may lead to degradation of the CMRR and THD. The unity-gain

buffer configuration is the most problematic as it traverses through the transition region if a sufficiently wide input

swing is required.

8.4.4 Design Optimization for Nanopower Operation

When designing for ultra-low power, choose system components carefully. To minimize current consumption,

select large-value resistors. Any resistors react with stray capacitance in the circuit and the input capacitance of

the operational amplifier (op amp). These parasitic RC combinations can affect the stability of the overall system.

A feedback capacitor may be required to assure stability and limit overshoot or gain peaking.

When possible, use AC coupling and AC feedback to reduce static current draw through the feedback elements.

Use film or ceramic capacitors because large electolytics may have static leakage currents in the tens to

hundreds of nanoamps.

8.4.5 Common-Mode Rejection

The CMRR for the TLV854x is specified in two ways so the best match for a given application may be used.

First, the CMRR of the device in the common-mode range below the transition region (VCM < (V+) – 1.2 V) is

given. This specification is the best indicator of the capability of the device when the application requires use of

one of the differential input pairs. Second, the CMRR at VS = 3.3 V over the entire common-mode range is

specified.

8.4.6 Output Stage

The TLV854x output voltage swings 20 mV from rails at a 3.3-V supply, which provides the maximum possible

dynamic range at the output. This is particularly important when operating on low supply voltages.

The TLV854x maximum output voltage swing defines the maximum swing possible under a particular output

load.