Bidirectional Current Sense Amplifier Features PWM Rejection

Maxim Integrated has introduced the MAX40056, a bidirectional current sense amplifier with patented pulse-width modulation (PWM) rejection. This high speed, wide-bandwidth amplifier extends Maxim’s family of precision, high-voltage current sense amplifiers into motor control applications.

Creating a motor control system requires precise current sensing and measurement of motor winding currents, says Maxim. A commonly used approach is to infer winding currents by performing ground or supply referenced measurements in the bridge circuit. Direct winding current measurement is a simpler and more accurate method, but the implementation is challenging due to the high common mode swing of the PWM signal. Adoption of this approach has been limited by poor PWM rejection and slow settling speed of existing solutions.

MAX40056 rejects PWM slew rates of greater than 500 V/µs and settles within 500 ns to provide 0.3 percent accurate, full-scale winding current measurement. The patented PWM rejection scheme achieves 4 times faster settling time than competitive offerings, allowing motor control designers to increase drive frequency or decrease minimum duty cycle without sacrificing measurement accuracy. Higher PWM frequency smooths out the current flow and reduces torque ripple, resulting in more efficient motor operation.

Accurate winding current measurement at low duty cycle helps reduce or virtually eliminate vibration when the motor is running at a slow speed. MAX40056 has a wide common mode voltage range of -0.1 V to +65 V and a protection range of -5 V to 70 V to ensure the inductive kickback does not damage the IC. With bi-directional sensing capability, it is well suited for DC motor control, base station, datacenter, battery stack and many other applications which require precise current measurements in noisy environments.

The MAX40056 is available at Maxim’s website for $1.19 (1000-up, FOB USA), also available from authorized distributors. The MAX40056EVKIT evaluation kit is available for $69.

Maxim Integrated |

LED Lighting Controller for Automotive

Texas Instruments has introduced the first 3-channel high-side linear automotive light-emitting diode (LED) controller without internal MOSFETs that gives designers greater flexibility for their lighting designs. The TPS92830-Q1’s novel architecture enables higher power and better thermal dissipation than conventional LED controllers, and are particularly beneficial for automotive LED lighting applications that require high performance and reliability.

TPS92830-Q1Conventional LED drivers integrate the MOSFET, which limits designers’ ability to customize features. With that type of driver, designers often must make significant design modifications to achieve the desired system performance. The TPS92830-Q1 LED controller’s flexible on-board features give designers the freedom to select the best MOSFET for their system requirements. With this new approach, designers can more quickly and efficiently optimize their lighting power designs for automotive system requirements and desired dimming features.

The on-chip pulse-width modulation (PWM) generator or PWM input enables flexible dimming. Designers can use either the analog control or PWM to manage an output current of more than 150 mA per channel, to power automotive rear combination lamps and daytime running lights.

By pairing the LED controller with an external MOSFET, the designer can achieve the required high power output while distributing the power across the controller and MOSFET to avoid system overheating. By retaining linear architecture, the TPS92830-Q1 provides improved electromagnetic interference (EMI) and electromagnetic compatibility (EMC) performance.

Advanced protection and built-in open and short detection features help designers meet original equipment manufacturer (OEM) system reliability requirements. The output current derating feature protects the external MOSFET under high voltage conditions to ensure system reliability.

Support tools include the TPS92830-Q1 3-Channel High-Current Linear LED Controller evaluation module. Engineers can jump-start automotive lighting systems designs using the TPS92830-Q1 with the EMC Compliant Automotive Daytime Running Light and Position Light Reference Design with LED Thermal Protection. The TPS92830-Q1 is now available through the TI store and authorized distributors. Offered in a thin small outline package (TSOP), it is priced at US$1.96 in 1,000-unit quantities.

Texas Instruments |