Output Voltage (V)

0

1

2

3

200

400

600

800

1000

1200

1400

INA281A1

INA281A2

INA281A3

INA281A4

INA281A5

Figure 6-1. Bandwidth vs Output Voltage

6.3.1.2 Low Input Bias Current

The INA281-Q1 inputs draw a 20-µA (typical) bias current at a common-mode voltage as high as 110 V, which

enables precision current sensing on applications that require lower current leakage.

6.3.1.3 Low VSENSE Operation

The INA281-Q1 operates with high performance across the entire valid VSENSE range. The zero-drift input

architecture of the INA281-Q1 provides the low offset voltage and low offset drift needed to measure low

VSENSE levels accurately across the wide operating temperature of –40 °C to +125 °C. Low VSENSE operation is

particularly beneficial when using low ohmic shunts for low current measurements, as power losses across the

shunt are significantly reduced.

6.3.1.4 Wide Fixed Gain Output

The INA281-Q1 gain error is < 0.5% at room temperature, with a maximum drift of 20 ppm/°C over the full

temperature range of –40 °C to +125 °C. TheINA281-Q1 is available in multiple gain options of 20 V/V, 50 V/V,

100 V/V, 200 V/V, and 500 V/V, which the system designer should select based on their desired signal-to-noise

ratio and other system requirements.

The INA281-Q1 closed-loop gain is set by a precision, low-drift internal resistor network. The ratio of these

resistors are excellently matched, while the absolute values may vary significantly. TI does not recommend

adding additional resistance around the INA281-Q1 to change the effective gain because of this variation,

however. The typical values of the gain resistors are described in Table 6-1.

Table 6-1. Fixed Gain Resistor

GAIN

R1

RL

20 (V/V)

25 kΩ

500 kΩ

50 (V/V)

10 kΩ

500 kΩ

100 (V/V)

10 kΩ

1000 kΩ

200 (V/V)

5 kΩ

1000 kΩ

500 (V/V)

2 kΩ

1000 kΩ

6.3.1.5 Wide Supply Range

The INA281-Q1 operates with a wide supply range from 2.7 V to 20 V. The output stage supports a wide output

range, while the INA281-Q1x1 (gain of 20 V/V) at a supply voltage of 20 V allows a maximum acceptable

differential input of 1 V. When paired with the small input offset voltage of the INA281-Q1, systems with very

wide dynamic ranges of current measurement can be supported.

INA281

SBOSA29A – JUNE 2020 – REVISED NOVEMBER 2023

www.ti.com

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