Tiny Amplifiers Enable Small High Performance System Designs

Texas Instruments has introduced what it claims is the industry’s smallest current-sense amplifier in a leaded package and the smallest, most accurate comparators with an internal 1.2-V or 0.2-V reference. Offered in industry-leading package options, the INA185 current-sense amplifier, and open-drain TLV4021 and push-pull TLV4041 comparators enable engineers to design smaller, simpler and more integrated systems while maintaining high performance. In addition, pairing the amplifier with one of the comparators produces the smallest, highest performing overcurrent detection solution in the industry, says TI.

These new devices are optimized for a variety of personal electronics, enterprise, industrial and communications applications, including peripherals, docking stations and notebooks. With a small-outline transistor (SOT)-563 package measuring 1.6 mm by 1.6 mm (2.5 mm2), the amplifier is 40% smaller than the closest competitive leaded packages. Featuring a 55-µV input offset that enables higher precision measurements at low currents, the INA185 enables the use of lower-value shunt resistors to cut system power consumption. Additionally, its 350-kHz bandwidth and 2-V/µS slew rate enable phase-current reproduction to enhance motor efficiency and save system power.

The precisely matched resistive gain network in the amplifier enables a maximum gain error as low as 0.2%, which contributes to robust performance over temperature and process variations. The device’s typical response time of 2 µs enables fast fault detection to prevent system damage.

System designers can add functionality in the same form factor and enable high-performance design with the TLV4021 and TLV4041 comparators. Available in an ultra-small die-size ball-grid array (DSBGA) 0.73-mm-by-0.73-mm package, the comparators’ integrated voltage reference saves board space while supporting precise voltage monitoring, which optimizes system performance.

The comparators can monitor voltages as low as the 0.2-V internal reference, and feature a high threshold accuracy of 1% across a full temperature range from -40°C to +125°C. Low 2.5-µA quiescent current delivers extended battery life for smart, connected devices. Fast propagation delay as low as 450 ns reduces latency, enabling power-conscious systems to monitor signals and respond quickly to fault conditions.

When using both the INA185 and the TLV4021 or TLV4041, engineers can shrink their total footprint to enable smaller systems. In combination, these devices produce the smallest, highest-performing overcurrent detection solution–15% smaller and 50 times faster than competitive devices. Pairing the amplifier with one of the comparators to support overcurrent detection on rails as high as 26 V delivers more headroom to better manage current spikes.

Production quantities of the INA185 are now available through the TI store and authorized distributors in a SOT-563 package, measuring 1.6 mm by 1.6 mm. Pricing starts at US$0.65 in 1,000-unit quantities. Production quantities of the push-pull TLV4041 and preproduction samples of the open-drain TLV4021 comparators are now available through the TI store and authorized distributors in an ultra-small DSBGA package, measuring 0.73 mm by 0.73 mm. Pricing for each comparator starts at US$0.39 in 1,000-unit quantities.

Texas Instruments | www.ti.com

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 | www.maximintegrated.com