With the adjustment factor equation including the device internal input resistance, this factor varies with each

gain version, as listed in Table 7-1. Each individual device gain error factor is listed in Table 7-2.

Table 7-1. Input Resistance

PRODUCT

GAIN

RINT (kΩ)

INA199x1

50

20

INA199x2

100

10

INA199x3

200

5

Table 7-2. Device Gain Error Factor

PRODUCT

SIMPLIFIED GAIN ERROR FACTOR

INA199x1

20,000

(17

R

+ 20,000

´

S)

INA199x2

10,000

(9

R

+ 10,000

´

S)

INA199x3

1000

R

+ 1000

S

The gain error that can be expected from the addition of the external series resistors can then be calculated

based on Equation 2:

Gain Error (%) = 100

(100

Gain Error Factor)

-

´

(2)

For example, using an INA199x2 and the corresponding gain error equation from Table 7-2, a series resistance

of 10-Ω results in a gain error factor of 0.991. The corresponding gain error is then calculated using Equation 2,

resulting in a gain error of approximately 0.89% solely because of the external 10-Ω series resistors. Using an

INA199x1 with the same 10-Ω series resistor results in a gain error factor of 0.991 and a gain error of 0.84%

again solely because of these external resistors.

7.4.2 Shutting Down the INA199 Series

Although the INA199 series does not have a shutdown pin, the low power consumption of the device allows the

output of a logic gate or transistor switch to power the INA199. This gate or switch turns on and turns off the

INA199 power-supply quiescent current.

However, in current shunt monitoring applications, there is also a concern for how much current is drained

from the shunt circuit in shutdown conditions. Evaluating this current drain involves considering the simplified

schematic of the INA199 in shutdown mode shown in Figure 7-3.

V+

OUT

GND

IN-

IN+

PRODUCT

R AND R

3

4

INA199x1

INA199x2

INA199x3

20 kW

10 kW

5 kW

C

BYPASS

Shutdown

Control

REF

Reference

Voltage

1 MW

R

3

1 MW

R

4

Supply

Load

R

SHUNT

Output

Copyright © 2017, Texas Instruments Incorporated

1-MΩ paths from shunt inputs to reference and the INA199 outputs.

Figure 7-3. Basic Circuit for Shutting Down the INA199 With a Grounded Reference

INA199

SBOS469H – APRIL 2009 – REVISED OCTOBER 2023

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