Nuts and Volts - February 2017

CURRENT-SENSE

AMPLIFIER

Texas Instruments (TI) has introduced a new current-sense amplifier for in-line motor phase current measurement that improves overall motor efficiency compared to existing current-sense amplifiers. The INA240 offers enhanced pulse-width modulation (PWM) rejection for systems running at up to 80V to support a variety of applications such as motor control, solenoid control, and power delivery systems. Key features and benefits include: • Enhanced PWM rejection for improved motor efficiency: The presence of high speed in-line PWM motor control systems requires high AC and DC accuracy. The INA240’s enhanced PWM rejection improves transient suppression and gives designers the ability to reduce their blanking time, optimize the motor control algorithm, and ultimately improve motor efficiency.

• Flexible for a variety of motor applications: The INA240 operates at PWM rates in excess of 100 kHz, with switching-edge rates as high as 10 V/ns while enabling system voltages as high as 80V. In addition, to address the needs for a wide range of systems, this device supports the negative voltages (-4V) induced by the inductive kickback of the motor.

• Industry-leading performance and accuracy: The INA240 has one of the industry’s best combinations of low offset voltage ( 5 µV), offset drift ( 50 nV/°C), gain error, and drift performance (0.05 percent and 0.5 ppm/°C, respectively). The device also provides an excellent AC common-mode rejection ratio (CMRR) of 93 dB at 50 kHz. The INA240 delivers performance over a wide range of operating conditions.

• Enhanced performance for any motor control solution: The INA240’s precision is showcased in a 48V 10A in-line three-phase high frequency Gallium Nitride (GaN) inverter for brushless motor reference design. This BoosterPack™plug-in module reference design is paired with a C2000™ LaunchPad™ kit, demonstrating how designers can use the INA240 and LMG5200 GaN half-bridge power stage to reduce switching losses over an extended temperature range up to 125°C, facilitate the use of higher PWM frequencies, and reduce heatsinking requirements.