The MAX9938 allows two methods of filtering to help

improve performance in the presence of input common-

mode voltage and input differential voltage transients.

Figure 1 shows a differential input filter.

The capacitor CIN between RS+ and RS- along with the

resistor RIN between the sense resistor and RS- helps

filter against input differential voltages and prevents

them from reaching the MAX9938.

The corner frequency of this filter is determined by the

choice of RIN, CIN, and the value of the input resis-

ferent gain options.

The value of RIN should be chosen to minimize its

effect on the input offset voltage due to the bias current

Placing RIN at the RS- input does not affect the gain

error of the device because the gain is given by the

Figure 2 shows the input common-mode filter.

Again, the corner frequency of the filter is determined

negligible effect on the device gain. If, for example, a fil-

ing upon the gain selection, the gain error is affected by

Ω) or 5% (G = 50V/V,

Ω).

1µA, 4-Bump UCSP/SOT23,

Precision Current-Sense Amplifier

8

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Figure 2. Input Common-Mode Filter

RS-

OUT

GND

RS+

MAX9938

LOAD

RS-

OUT

GND

RS+

MAX9938

LOAD

Figure 1. Differential Input Filter