INA180B2 datasheet(26/53 Pages) TI2

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One method of calculating the total error is to add the gain error to the percentage contribution of the offset error.

However, in this case, the gain error and the offset error do not have an influence or correlation to each other. A

more statistically accurate method of calculating the total error is to use the RSS sum of the errors, as shown in

Equation 7:

Total Error (%) =

Total Gain Error (%) + Total Offset Error (%)

(7)

After applying Equation 7, the total current sense error at maximum current is calculated to be 1.25%, and that is

less than the design example requirement of 1.5%.

The INA180A4 (gain = 200) also has a bandwidth of 105 kHz that meets the small-signal bandwidth requirement

of 80 kHz. If higher bandwidth is required, lower-gain devices can be used at the expense of either reduced

output voltage range or an increased value of RSENSE.

9.2.3 Application Curve

Figure 9-4 shows an example output response of a unidirectional configuration. The device output swing is

limited by ground; therefore, the output is biased to this zero output level. The output rises above ground for

positive differential input signals, but cannot fall below ground for negative differential input signals.

Time (500 µs/div)

Output

Ground

0 V

Figure 9-4. Output Response

9.3 Power Supply Recommendations

The input circuitry of the INAx180 accurately measures beyond the power-supply voltage, VS. For example, VS

can be 5 V, whereas the bus supply voltage at IN+ and IN– can be as high as 26 V. However, the output voltage

range of the OUT pin is limited by the voltages on the VS pin. The INAx180 also withstand the full differential

input signal range up to 26 V at the IN+ and IN– input pins, regardless of whether or not the device has power

applied at the VS pin.

9.3.1 Common-Mode Transients Greater Than 26 V

With a small amount of additional circuitry, the INAx180 can be used in circuits subject to transients higher than

26 V, such as automotive applications. Use only Zener diodes or Zener-type transient absorbers (sometimes

referred to as transzorbs)—any other type of transient absorber has an unacceptable time delay. Start by adding

a pair of resistors as a working impedance for the Zener diode, as shown Figure 9-5. Keep these resistors as

small as possible; most often, around 10 Ω. Larger values can be used with an effect on gain that is discussed

in the Signal Filtering section. This circuit limits only short-term transients; therefore, many applications are

satisfied with a 10-Ω resistor along with conventional Zener diodes of the lowest acceptable power rating. This

combination uses the least amount of board space. These diodes can be found in packages as small as

SOT-523 or SOD-523.

INA180, INA2180, INA4180

SBOS741H – APRIL 2017 – REVISED JULY 2022

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