The M54544AL is an IC for driving a smallsize bi-directional motor that rotates in both forward and reverse directions. When both inputs 1 and 2 are set to low-level, outputs 1 and 2 are set to "OFF". When input 1 is set to high-level and input 2 is set to lowlevel, output 1 is set to high-level and output 2 is set to low-level (forward rotation status). When input 1 is set to low-level and input 2 is set to high-level, output 1 is set to low-level and output 2 is set to high-level (reverse rotation). When both inputs 1 and 2 are set to high-level, both outputs 1 and 2 are set to low-level (brake status). The power supply (VCC) to the control circuit and the power supply (VCC') for output are independently provided. The rotating speed of the motor can be therefore changed by using VCC and VCC' as different power supplies and by making VCC or VCC' variable. If the motor resistance is high (light load and small driving current: tens of mA), and VCC is larger than VCC', current does not flow backward from the V CC pin to VCC' pin. |