Precision control of automotive proportional solenoids is necessary to achieve the precise control in an automatic transmission, in electronic fuel injectors, and in several automotive actuator applications. In proportional solenoids, the current flowing through the coil is directly oportional to the magnetic field generated. The designer can estimate armature position by knowing the current that is flowing through the solenoid. By forming a closed-loop solenoid control with high-accuracy current sensors, the designer is able to control the proportional olenoid in a precise manner. This order of control implies that highaccuracy current sensors are critical to achieve precise control of solenoids. Some of the main aspects to consider when selecting a current sensor are less offset, less drift, and higher pulse-width-modulation (PWM) rejection ration. By combining the above three features, this reference design shows a way to precisely measure the current flowing through the solenoid using TI's current shunt monitoring portfolio.
- Uncalibrated accuracy: less than 1% for more than 10 mA over temperature (–40°C to 125°C)
- Suitable for various solenoid current ranges
- Low drift, high precision
- High-side drive, high-side solenoid monitor
- Enhanced PWM rejection facilitates uniform current profile
- Lowers blanking time and enables accurate measurements at lower duty cycle