4

3

2

1

0

–1

2

3

4

–

–

–

–500

1000

Time (µs)

–250

0

750

250

500

V

I

V

O

16

OPA320-Q1, OPA2320-Q1

SLOS884B – SEPTEMBER 2014 – REVISED DECEMBER 2018

www.ti.com

Product Folder Links: OPA320-Q1 OPA2320-Q1

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Copyright © 2014–2018, Texas Instruments Incorporated

7.4 Device Functional Modes

7.4.1 Rail-to-Rail Input

The OPAx320-Q1 feature true rail-to-rail input operation, with supply voltages as low as ±0.9 V (1.8 V). The

design of the OPAx320-Q1 amplifiers include an internal charge-pump that powers the amplifier input stage with

an internal supply rail at approximately 1.6 V above the external supply (V+). This internal supply rail allows the

single differential input pair to operate and remain very linear over a very wide input common-mode range. A

unique zero-crossover input topology eliminates the input offset transition region typical of many rail-to-rail,

complementary input stage operational amplifiers. This topology allows the OPAx320-Q1 to provide superior

common-mode performance (CMRR > 110 dB, typical) over the entire common-mode input range, which extends

100 mV beyond both power-supply rails. When driving analog-to-digital converters (ADCs), the highly linear V(CM)

range of the OPAx320-Q1 provides maximum linearity and lowest distortion.

7.4.2 Phase Reversal

The OPAx320-Q1 op amps are designed to be immune to phase reversal when the input pins exceed the supply

voltages, and thus provide further in-system stability and predictability. Figure 35 shows the input voltage

exceeding the supply voltage without any phase reversal.

VS = ±2.5 V

Figure 35. No Phase Reversal