Data Sheet

AD8417

OUTPUT OFFSET ADJUSTMENT

The output of the AD8417 can be adjusted for unidirectional or

bidirectional operation.

UNIDIRECTIONAL OPERATION

Unidirectional operation allows the AD8417 to measure currents

through a resistive shunt in one direction. The basic modes for

unidirectional operation are ground referenced output mode

For unidirectional operation, the output can be set at the negative

differential input is 0 V. The output moves to the opposite rail

when a correct polarity differential input voltage is applied. The

required polarity of the differential input depends on the output

voltage setting. If the output is set at the positive rail, the input

polarity must be negative to decrease the output. If the output is

set at ground, the polarity must be positive to increase the output.

Ground Referenced Output Mode

When using the AD8417 in ground referenced output mode, both

referenced inputs are tied to ground, which causes the output to sit

at the negative rail when there are zero differential volts at the input

(see Figure 27).

–

+

R1

OUT

GND

AD8417

R2

R3

R4

–IN

+IN

Figure 27. Ground Referenced Output

to the positive supply. It is typically used when the diagnostic

scheme requires detection of the amplifier and the wiring before

power is applied to the load (see Figure 28).

–

+

R1

OUT

GND

AD8417

R2

R3

R4

–IN

+IN

BIDIRECTIONAL OPERATION

Bidirectional operation allows the AD8417 to measure currents

through a resistive shunt in two directions.

In this case, the output is set anywhere within the output range.

Typically, it is set at half-scale for equal range in both directions.

In some cases, however, it is set at a voltage other than half scale

when the bidirectional current is nonsymmetrical.

Adjusting the output is accomplished by applying voltage(s) to

resistors that connect to an internal offset node. There is no

operational difference between the pins.

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