OPA607 datasheet(19/48 Pages) TI

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8.3.3 Input and ESD Protection

When the primary design goal is a linear amplifier with high CMRR, do not exceed the op amp input common-

mode voltage range (VCM). This CMRR is used to set the common-mode input range specifications in Section

7.5. The typical VCM specifications for the OPAx607 devices are from the negative rail to 1.1 V below the positive

rail. Assuming the op amp is in linear operation, the voltage difference between the input pins is small (ideally

0 V) and the input common-mode voltage can be analyzed at either input pin; the other input pin is assumed to

be at the same potential. The voltage at VIN+ is easy to evaluate. In a noninverting configuration (Figure 8-1) the

input signal, VIN+, must not exceed the VCM rating. However, in an inverting amplifier configuration, VIN+ must be

connected to the voltage within VCM. The input signal applied at VIN- can be any voltage, such that the output

voltage swings with a headroom of 10 mV from either of the supply rails.

The input voltage limits have fixed headroom to the power rails and track the power-supply voltages. For single

5-V supply, the linear input voltage range is 0 V to 3.9 V and with a 2.2-V supply this range is 0 V to 1.1 V. The

headroom to each power-supply rail is the same in either case: 0 V and 1.1 V. A weak NMOS input pair from

VIN+ to VIN+ – 1.1 V ensures that an output phase reversal issue does not occur when the VCM is violated.

Power-Supply

ESD Cell

VSS

VDD

TVS

VS+

OPAx607

V6¤

OUT

IN+

IN-

Figure 8-4. Internal ESD Structure

The OPAx607 devices also incorporate internal electrostatic discharge (ESD) protection circuits on all pins. For

the input and output pins, this protection primarily consists of current-steering diodes connected between the

input and power-supply pins. These ESD protection diodes provides input overdrive protection, as long as the

current is limited with a series resistor to 10 mA, as stated in Section 7.1. Figure 8-1 shows a series input

resistor can be added to the driven input to limit the input current.

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OPA607, OPA2607

SBOS981J – OCTOBER 2019 – REVISED APRIL 2021

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OPA607 Datasheet(PDF) 19 Page - Texas Instruments