Bidirectional Current Sense Amplifier with PWM-Rejection

The MAX40056 is a bidirectional current-sense amplifier with an input common-mode range that extends from -0.1V to +65V together with protection against negative inductive kickback voltages to -5V. This CSA is well-suited for phase current monitoring of inductive loads, such as motors and solenoids, where pulse width modulation is used to control the drive voltage and current. The MAX40056 uses an improved technique to help reject common-mode input PWM edges with slew rates up to and beyond ±500V/µs. Common mode rejection ratio (CMRR) is typically 60dB (50V, ±500V/µs input) and 140dB DC, typical.

The MAX40056 has an internal +1.5V reference for use with a nominal +3.3V power supply. The reference can also be used to drive an adjoining differential ADC. The reference is used to offset the output to indicate the direction of the input sensed current. The REF pin can source current into external loads and helps to avoid the performance compromises resulting from routing reference voltages across noisy PCBs. Alternatively, for higher supply voltages and higher full-scale output swings, the internal reference can be overridden by a higher voltage, external reference.

The internal or external reference can be used to define the trip threshold for the integrated overcurrent comparator. This can provide immediate indication of an overcurrent fault condition.

The MAX40056 operates over the full -40°C to +125°C temperature range and runs from a supply voltage of +2.7V to +5.5V. It is offered in a 2.02mm x 1.4mm 8-pin wafer-level package (WLP) and 8-pin µMAX packages.

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Applications

* Automotive * Battery Stack Monitors * Current Monitoring of Inductive Loads * PWM H-Bridge Motor In-line/In-phase/Winding Current Sensing * Solenoid Current Sensing

* AEC-Q100

* Fast, 500ns PWM Edge recovery from 500V/µs PWM Edges

* 60dB AC CMRR Rejection at 50V, ±500V/µs PWM Edges

* 140dB DC CMRR Rejection

* -0.1V to +65V Input Voltage Range

* -5V to +70V Protective Immunity

* 300kHz, -3dB Bandwidth

* Multiple Gain Options; 10V/V, 20V/V, 50V/V

* Internal, 1% Reference for Bidirectional Offset

* 5µV (Typ) Input Offset Voltage

* Rail-to-Rail Output

* 2.02mm x 1.4mm, 8-bump WLP and 8-pin µMAX

* -40°C to +125°C Temperature Range