INA210 datasheet(10/17 Pages) TI

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USING THE INA210 WITH COMMON-MODE

REF INPUT IMPEDANCE EFFECTS

Output

INA21x

Load

Supply

ADC

V+

OUT

GND

IN-

IN+

BYPASS

0.01mF

0.1mF

+2.7Vto+26V

REF

RSHUNT

INA21x

V+

OUT

GND

IN-

IN+

BYPASS

Shutdown

Control

REF

Reference

Voltage

Supply

Load

SHUNT

Output

1MW

PROTECT

10W

PROTECT

10W

1MW

INA210

,, INA211

INA212, INA213

INA214

SBOS437A – MAY 2008 – REVISED JUNE 2008............................................................................................................................................................... www.ti.com

As a final note, when the device is powered up, there

is an additional, nearly constant, and well-matched

TRANSIENTS ABOVE 26V

µA that flows in each of the inputs as long as the

With a small amount of additional circuitry, the

shunt common-mode voltage is 3V or higher. Below

INA210-INA214 series can be used in circuits subject

2V common-mode, the only current effects are the

to transients higher than 26V, such as automotive

result of the 1M

Ω resistors.

applications. Use only zener diode or zener-type

transient

absorbers

(sometimes

referred

Transzorbs)— any other type of transient absorber

has an unacceptable time delay. Start by adding a

As with any difference amplifier, the INA210-INA214

pair of resistors as shown in Figure 27 as a working

series common-mode rejection ratio is affected by

impedance for the zener. It is desirable to keep these

any impedance present at the REF input. This

resistors as small as possible, most often around

concern is not a problem when the REF pin is

Ω. Larger values can be used with an effect on

connected directly to most references or power

gain that is discussed in the section on input filtering.

supplies. When using resistive dividers from the

Because

this

circuit

limiting

only

short-term

power supply or a reference voltage, the REF pin

transients, many applications are satisfied with a 10

Ω

should be buffered by an op amp.

resistor along with conventional zener diodes of the

In systems where the INA210-INA214 output can be

lowest

power

rating

that

can

found.

This

sensed differentially, such as by a differential input

combination uses the least amount of board space.

analog-to-digital converter (ADC) or by using two

These diodes can be found in packages as small as

separate

ADC

inputs,

the

effects

external

SOT-523 or SOD-523.

impedance on the REF input can be cancelled.

Figure 26 depicts a method of taking the output from

the INA210-INA214 by using the REF pin as a

reference.

Figure 26. Sensing INA210-INA214 to Cancel

Figure 27. INA210-INA214 Transient Protection

Effects of Impedance on the REF Input

Using Dual Zener Diodes

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Product Folder Link(s): INA210 INA211 INA212 INA213 INA214

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