MAX40056FAUA+ Bidirectional Current Sense Amplifier with PWM-Rejection
Maxim’s current sense amplifier is well-suited for phase current monitoring of inductive loads such as motors and solenoids
Maxim’s MAX40056FAUA+ is a bidirectional current-sense amplifier with an input common-mode range that extends from -0.1 V to +65 V with protection against negative inductive kickback voltages to -5 V. This current sense amplifier is well-suited for phase current monitoring of inductive loads, such as motors and solenoids, where pulse width modulation (PWM) 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 ±500 V/µs. Common mode rejection ratio (CMRR) is typically 60 dB (50 V, ±500 V/µs input) and 140 dB DC, typical.
The MAX40056FAUA+ has an internal +1.5 V reference for use with a nominal +3.3 V 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 MAX40056FAUA+ operates over the full -40°C to +125°C temperature range and runs from a supply voltage of +2.7 V to +5.5 V.
- Fast 2 µs PWM edge recovery (1%) from 500 V/µs PWM edges
- 60 dB AC CMRR rejection at 50 V, ±500 V/µs PWM edges
- 140 dB DC CMRR rejection
- -0.1 V to +65 V input voltage range
- -5 V to +70 V protective immunity
- 300 kHz, -3 dB bandwidth
- Multiple gain options; 10 V/V, 20 V/V, 50 V/V
- Internal 1% reference for bidirectional offset
- 5 µV (typ) input offset voltage
- Rail-to-rail output
- 2.02 mm x 1.4 mm WLP-8 and 8-pin µMAX
- -40°C to +125°C temperature range
- Battery stack monitors
- Current monitoring of inductive loads
- PWM H-bridge motor in-line/in-phase/winding current sensing
- Solenoid current sensing