Typical Application Circuits

Solenoid Current Measurement

A solenoid is used to convert electrical energy into a mechanical movement to position an object like a car window. The

following figure shows the example circuit that uses the MAX49921 to measure the current in the solenoid with a low-

side shunt-sensing resistor. Even if the power supply is connected in reverse, the MAX49921 can still withstand up to

-42V without needing a reverse-protection diode.

5V

POWER SUPPLY

LEVEL

SHIFTING

GND

MAX49921

MAX49921

RS+

RS-

OUT

SOLENOID

CONTROLLER

ADC

DC Motor Current Measurement

The following figure shows an example of high-side current sensing in a DC motor with the MAX49921. The high

common-mode voltage range of the MAX49921 makes it capable of surviving the kick-back voltages in motor switching.

The device is also protected up to -42V in case a reverse-battery connection occurs.

5V

POWER

SUPPLY

LEVEL

SHIFTING

GND

MAX49921

MAX49921

RS+

RS-

OUT

DC

MOTOR

ADC

M

M

CONTROLLER

MAX49921

0 to 70V, High-Precision Current-Sense Amplifier

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Analog Devices | 12