INA181 datasheet(21/47 Pages) TI1

21 / 47 page

CBYPASS

0.1 µF

2.7 V to 5.5 V

Shutdown

RPULL-UP

10 k

RSENSE

GND

Load

IN±

IN+

OUT

REF

Bus Voltage

±0.2 V to +26 V

Output

Single-Channel

TI Device

INA181-Q1, INA2181-Q1, INA4181-Q1

www.ti.com

SLYS018A – APRIL 2018 – REVISED JULY 2018

INA2181-Q1 INA4181-Q1

Submit Documentation Feedback

Device Functional Modes (continued)

8.4.5 Shutdown Mode

Although the INAx181-Q1 do not have a shutdown pin, the low power consumption of these devices allows the

output of a logic gate or transistor switch to power the INAx181-Q1. This gate or switch turns on and off the

INAx181-Q1 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 INAx181-Q1 in shutdown mode, as shown in Figure 46.

Figure 46. Basic Circuit to Shut Down the INA181-Q1 With a Grounded Reference

There is typically more than 500 k

Ω of impedance (from the combination of 500-kΩ feedback and

input gain set resistors) from each input of the INAx181-Q1 to the OUT pin and to the REF pin. The amount of

current flowing through these pins depends on the voltage at the connection. For example, if the REF pin is

grounded, the calculation of the effect of the 500 k

Ω impedance from the shunt to ground is straightforward.

However, if the reference is powered while the INAx181-Q1 is in shutdown mode, instead of assuming 500 k

Ω to

ground, assume 500 k

Ω to the reference voltage.

Regarding the 500-k

Ω path to the output pin, the output stage of a disabled INAx181-Q1 does constitute a good

path to ground. Consequently, this current is directly proportional to a shunt common-mode voltage present

across a 500-k

Ω resistor.

As a final note, as long as the shunt common-mode voltage is greater than VS when the device is powered up,

there is an additional and well-matched 55-µA typical current that flows in each of the inputs. If less than VS, the

common-mode input currents are negligible, and the only current effects are the result of the 500-k

Ω resistors.

INA181 Datasheet(PDF) 21 Page - Texas Instruments

INA181 Datasheet(HTML) 21 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

Datasheet Download

Link URL