Maxim Releases Bidirectional Current-Sense Amplifier MAX40056 with PWM Suppression

Maxim Integrated Products, Inc. (NASDAQ: MXIM) announced on June 25 that the MAX40056 bidirectional current sense amplifier, a proprietary pulse width modulation (PWM) suppression technology, helps engineers improve motor efficiency and reduce vibration. This high-speed, wideband amplifier extends Maxim's leadership in high-precision, high-voltage current-sense to motor control applications.

The motor control system requires high precision current sensing and current measurement of the motor windings. A common method is to measure the winding current by grounding the bridge circuit or the power reference. Direct measurement of winding current is a simpler, more accurate measurement, but due to the high common-mode swing of the PWM signal, implementation difficulties. The current scheme has a slower PWM suppression performance and a slower establishment speed, which restricts the popularity of this method.

Figure: Block diagram of the MAX40056.

The MAX40056 rejects PWM slew rates above 500V/μs and completes signal setup in 500ns for full-scale winding current measurements with up to 0.3% accuracy. Compared to competing products, proprietary PWM suppression technology increases setup time by a factor of four, allowing motor control designers to increase the drive frequency of the motor or reduce the minimum duty cycle without compromising measurement accuracy. The higher PWM frequency helps stabilize current and reduce torque ripple for higher motor efficiency. Accurate measurement of low duty cycle winding currents helps to reduce or substantially eliminate vibration during low speed operation of the motor. The MAX40056 supports a wide common-mode voltage range of -0.1V to +65V and a protection range of -5V to 70V to ensure that the IC does not damage the IC during kickback. With its two-way detection capability, ICs are ideal for DC motor control, base stations, data centers, battery packs, and other applications that require high-precision current measurement in noisy environments.

Main advantage

• Fast settling time: Common mode PWM signal high rejection patented technology, the fastest settling time of less than 500ns.

• Highest precision: High-precision direct measurement of motor winding current, PWM frequency is 4 times higher than competitive products, or duty cycle is 4 times lower.

• Improve performance: Improve motor efficiency and reduce vibration.


• “Complicated, highly sensitive systems such as autonomous vehicles require extremely high-precision detection feedback to support a high level of functionality and safety,” said Rahul Kumar, an analyst at Allied Market Research. “The industry's need for high-precision motor control solutions. Increasingly high, especially the auto market is expected to grow to $556.67 billion by 2026."

• “The MAX50056's high PWM rejection and fast settling advantages allow for current measurements synchronized with the motor windings for maximum precision and optimal control in sensitive applications,” said Dimitry Goder, Director of Product Applications and Definitions, Maxim Integrated Core Products. Its unique design architecture leverages the high performance of motor control applications to drive future market innovations."

Supply and price

• The MAX40056 is priced at $1.19 (1000 sheets, FOB USA) and can be purchased through the Maxim website and licensed dealers.

• The MAX40056EVKIT evaluation kit is available for $69.