OPA992 datasheet(19/51 Pages) TI

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7.3 Feature Description

7.3.1 Input Protection Circuitry

The OPAx992-Q1 uses a special input architecture to eliminate the requirement for input protection diodes

but still provides robust input protection under transient conditions. Figure 7-1 shows conventional input diode

protection schemes that are activated by fast transient step responses and introduce signal distortion and

settling time delays because of alternate current paths, as shown in Figure 7-2. For low-gain circuits, these

fast-ramping input signals forward-bias back-to-back diodes, causing an increase in input current and resulting in

extended settling time.

OPAx992-Q1

40 V

~0.7 V

VOUT

V+

Conventional Input Protection

Limits Differential Input Range

OPAx992-Q1 Provides Full 40-V

Differential Input Range

VIN+

VIN

VOUT

V+

VIN+

VIN

Figure 7-1. OPAx992-Q1 Input Protection Does Not Limit Differential Input Capability

Input Low-Pass Filter

Ron_mux

Sn+1

Simplified Mux Model

RFILT

CFILT

Vn = 10 V

Vn+1 = ±10 V

10 V

±10 V

Buffer Amplifier

Idiode_transient

10 V

~±9.3 V

VIN+

VIN±

~0.7 V

VOUT

±10 V

Ron_mux

Figure 7-2. Back-to-Back Diodes Create Settling Issues

The OPAx992-Q1 family of operational amplifiers provides a true high-impedance differential input capability

for high-voltage applications using a patented input protection architecture that does not introduce additional

signal distortion or delayed settling time, making the device an excellent op amp for multichannel, high-switched,

input applications. The OPAx992-Q1 tolerates a maximum differential swing (voltage between inverting and

non-inverting pins of the op amp) of up to 40 V, making the device designed for use as a comparator or in

applications with fast-ramping input signals such as data-acquisition systems; see the TI TechNote MUX-Friendly

Precision Operational Amplifiers for more information.

www.ti.com

OPA992-Q1, OPA2992-Q1, OPA4992-Q1

SBOSAC9D – AUGUST 2022 – REVISED APRIL 2023

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Product Folder Links: OPA992-Q1 OPA2992-Q1 OPA4992-Q1

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