INA821 datasheet(20/50 Pages) TI2

20 / 50 page

49.4 k

10 k

24.7 k

10 k

24.7 k

Overvoltage

Protection

Overvoltage

Protection

REF

+VS

V-

OUT

V+

-VS

-IN

+IN

49.4 k

REF

G V

INA821

SBOS893D – AUGUST 2018 – REVISED JUNE 2020

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8.3 Feature Description

8.3.1 Setting the Gain

Figure 55 shows that the gain of the INA821 is set by a single external resistor (RG) connected between the RG

pins (pins 1 and 8).

Figure 55. Simplified Diagram of the INA821 With Gain and Output Equations

The value of RG is selected according to:

(1)

Table 2 lists several commonly used gains and resistor values. The 49.4-k

Ω term in Equation 1 is a result of the

sum of the two internal 24.7-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 INA821. As shown in Figure 55 and explained in more details in the Layout section,

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 2. Commonly-Used Gains and Resistor Values

DESIRED GAIN

RG (Ω)

NEAREST 1% RG (Ω)

49.4 k

49.9 k

12.35 k

12.4 k

5.489 k

5.49 k

2.600 k

2.61 k

1.008 k

1 k

100

499

200

248

249

500

100

1000

49.4

49.9

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