8.3 Feature Description

8.3.1 Gain-Setting Function

pins (pins 1 and 8).

+

–

+

–

+

–

50 k

50 k

50 k

50 k

50 k

50 k

Overvoltage

Protection

RG

REF

+VS

VS

OUT

+VS

VS

IN

+IN

RG

+

–

+

+

Overvoltage

Protection

Figure 8-1. Simplified Diagram of the INA823 With Gain and Output Equations

The gain of the INA823 can be calculated with Equation 1:

(1)

(2)

Table 8-1 lists several commonly used gains and resistor values. The 100-kΩ term in Equation 1 is a result of the

sum of the two internal 50-kΩ feedback resistors. These on-chip resistors are laser-trimmed to accurate absolute

values. The accuracy and temperature coefficients of these resistors are included in the gain accuracy and drift

specifications of the Section 7.5. As shown in Figure 8-1 and explained in more details in Section 11, make sure

to connect low-ESR, 0.1-µF ceramic bypass capacitors between each supply pin and ground that are placed as

close to the device as possible.

Table 8-1. Commonly Used Gains and Resistor Values

DESIRED GAIN

CALCULATED GAIN ERROR (%)

1

Not connected

Not connected

2

100 k

0

5

24.9 k

2

10

11 k

0.9

20

5.23 k

0.6

33

3.09 k

1.09

50

2.05 k

0.44

65

1.58 k

1.09

100

1.02 k

0.96

200

499

0.7

500

200

0.2

1000

100

0.1

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INA823

SBOSA75A – JULY 2021 – REVISED JULY 2021

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