G

10 000

G

1

R

= +

A1

A2

A3

6kΩ

6kΩ

6

5

4

7

2

1

8

3

6kΩ

6kΩ

V

V

R

G

V+

V–

V+

V–

INA217

G = 1 +

10000

R

G

5kΩ

5kΩ

V

OUT

V

O

Sometimes Shown in

Simplified Form:

NOTE: (1) NC = No Connection.

REF

0.1µF

0.1µF

R

G

INA217

GAIN

R

G

(V/V)

(dB)

(Ω)

1

0

NC

(1)

2

6

10000

5

14

2500

10

20

1111

20

26

526

50

34

204

100

40

101

200

46

50

500

54

20

1000

60

10

2000

66

5

V

V

INA217

www.ti.com

SBOS247C – JUNE 2002 – REVISED NOVEMBER 2015

Feature Description (continued)

Figure 13. Basic Circuit Connections

7.3.2 Gain-Set Resistor

laser-trimmed to 5-k

Ω within approximately ±0.2%. Equation 1 shows the gain equation for the INA217.

(1)

The temperature coefficient of the internal 5-k

Ω resistors is approximately ±25 ppm/°C. Accuracy and TCR of the

sensitive input nodes.

7.3.3 Noise Performance

The INA217 provides very low noise with low-source impedance. Its 1.3-nV/M

√Hz voltage noise delivers near-

theoretical noise performance with a source impedance of 200

Ω. The input stage design used to achieve this

low noise results in relatively high input bias current and input bias current noise. As a result, the INA217 may

not provide the best noise performance with a source impedance greater than 10 k

Ω. For source impedance

greater than 10 k

Ω, other instrumentation amplifiers may provide improved noise performance.

7.3.4 Input Considerations

Very low source impedance (less than 10

Ω) can cause the INA217 to oscillate. This depends on circuit layout,

signal source, and input cable characteristics. An input network consisting of a small inductor and resistor, as

shown in Figure 14, can greatly reduce any tendency to oscillate. This is especially useful if a variety of input

sources are to be connected to the INA217. Although not shown in other figures, this network can be used as

needed with all applications shown.

Copyright © 2002–2015, Texas Instruments Incorporated

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