INA821 datasheet(25/45 Pages) TI

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8.2.1.2 Detailed Design Procedure

8.2.1.2.1 Operating Voltage

The INA592 operates from single (4.5 V to 36 V) or dual (±2.25 V to ±18 V) supplies with excellent performance.

Specifications are production tested with 5-V and ±15-V supplies. Most behavior remains unchanged throughout

the full operating voltage range. Parameters that vary significantly with operating voltage are shown in the

Section 6.7. The internal op amp in the INA592 is a single-supply design. This design allows linear operation

with the op amp common-mode voltage equal to, or slightly less than V– (or single-supply ground). Although

input voltages on pins 2 and 3 that are bless than the negative supply voltage do not damage the device,

operation in this region is not recommended. Transient conditions at the inverting input terminal less than the

negative supply can cause a positive feedback condition that could lock the device output to the negative rail.

The INA592 can accurately measure differential signals that are greater than the positive power supply. For

example in G = ½, the linear common-mode range extends to nearly three times the positive power-supply

voltage; see the Typical Characteristics as well as Section 8.2.1.2.3.

8.2.1.2.2 Offset Voltage Trim

The INA592 is production trimmed for low offset voltage and drift. Most applications require no external offset

adjustment. Figure 8-2 shows an optional circuit for trimming the output offset voltage. The output is referred to

the output reference terminal (pin 1), which is normally grounded. A voltage applied to the REF pin is summed

with the output signal. This summing operation can be used to null offset voltage. To maintain good common-

mode rejection, the source impedance of a signal applied to the REF pin must be less than 8 Ω. For low

impedance at the REF pin, the trim voltage can be buffered with an op amp, such as the OPA177.

INA592

O = V3 – V2

Offset Adjustment

Range = ±500 µV

Ref

8 W

R = 237 kW

8 W

100 kW

+15 V

–15 V

NOTE: For ±750 µV range, R = 158 k .

Figure 8-2. Offset Adjustment

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INA592

SBOS914E – OCTOBER 2018 – REVISED FEBRUARY 2021

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INA821 Datasheet(PDF) 25 Page - Texas Instruments