Detailed Description

The MAX9918/MAX9919/MAX9920 are single-supply,

high-accuracy uni-/bidirectional current-sense amplifiers

with a high common-mode input range that extends from

-20V to +75V. The MAX9918/MAX9919/MAX9920’s input

stage utilizes a pair of level shifters allowing a wide

common-mode operating range when measuring the

The first level shifter accommodates the upper common-

mode operating range from +2V to +75V. When the

common-mode voltage falls below +2V, the second level

shifter is used to accommodate negative voltages down

to -20V.

ence voltage where it is then amplified with an instru-

mentation amplifier. The instrumentation amplifier

configuration provides high precision with input offset

voltages of 400µV (max). Indirect feedback of the

instrumentation amplifier allows the gain to be adjusted

with an external resistive-divider network on the

MAX9918/MAX9920. The MAX9919 is a fixed gain

device available with laser-trimmed resistors for gains

of 45V/V (MAX9919F) and 90V/V (MAX9919N).

The MAX9918/MAX9919 operate with a full-scale sense

voltage of 50mV. The input stage of the MAX9920 pro-

vides an attenuation factor of 4, enabling a full-scale

sense voltage of 200mV.

-20V to +75V Input Range, Precision

Uni-/Bidirectional, Current-Sense Amplifiers

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13

Pin Description

PIN

NAME

FUNCTION

1

RS+

Positive Current-Sensing Input. Power side connects to external sense resistor.

2

RS-

Negative Current-Sensing Input. Load side connects to external sense resistor.

3

SHDN

Active-High Shutdown Input. Connect to GND for normal operation.

4

GND

Ground

5

OUT

6FB

Feedback Input. Connect FB to a resistive-divider network to set the gain for the MAX9918 and

MAX9920. See the Adjustable Gain (MAX9918/MAX9920) section for more information. Leave FB

unconnected for the MAX9919 for proper operation.

7

REFIN

operation.

—EP

Exposed Pad. Connect to a large-area contiguous ground plane for improved power dissipation. Do

not use as the only ground connection for the part.

8 SOIC-EP

TOP VIEW

MAX9918

MAX9919

MAX9920

FB

OUT

8

7

REFIN

6

5

GND

1

2

RS-

SHDN

RS+

3

4

EP*

+

*EXPOSED PAD. CONNECT EP TO SOLID GROUND FOR

PROPER THERMAL AND ELECTRICAL PERFORMANCE.

Pin Configuration