What about valve control? If precise position and not just on and off are needed, a stepper motor is most commonly used. For on and off, H-bridge drivers for brush DC motors are chosen. There are dual H-bridge parts available, so it is necessary to know how many channels will be controlled. Once the motor type is identified, the supply voltage range and current requirements can be compared to the charts on the previous slides. For the latest information, the designer should check on the web. To further narrow down the selection, obtain the information needed to answer questions four through six.