Motor driver ICs Stepping motor driver BA6845FS The BA6845FS is a stepping motor driver with a maximum output current of 1.0A. The logic input allows three output modes : forward, reverse, and power save. The IC has a low output saturation voltage and is capable of driving motors at low supply voltage. Applications Stepping motors for floppy disk drives Features 1) Low output saturation voltage. 2) Power save circuit. 3) Thermal shutdown circuit. Absolute maximum ratings (Ta = 25C) Recommended operating conditions (Ta = 25C) 735 Motor driver ICs Block diagram 736 BA6845FS Motor driver ICs BA6845FS Pin descriptions Input / output circuits (all resistances are typical values) 737 Motor driver ICs Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 5V) Truth table 738 BA6845FS Motor driver ICs BA6845FS Application example Operation notes (1) Control logic pins Do not apply voltage to control logic pins (pins 4, 5, 12, and 13) when the VCC voltage is not applied to the IC. The voltage of each pin should be less than VCC, if applied, and should be more than the ground voltage. (2) PCB arrangement When changing the rotational direction of a motor, a large current of up to a few hundred milliamperes can flow between the motor power supply (pins 11 and 14) and MGND (pins 1 and 8). Depending on the application, this large output current may flow back to input pins, resulting in output oscillation or other malfunctions. Make sure that your design does not allow a common impedance between the large current output lines and the input section. Suppress the power supply impedance to low levels, otherwise output oscillation may occur. (3) Package power dissipation The power dissipated by the IC varies widely with the supply voltage and the output current. Give full consideration to the package power dissipation rating when setting the supply voltage and the output current. (4) Ground pins Pins 1, 3, 6, and 8 should have the lowest potential (ground potential) in the IC. (5) Thermal shutdown circuit This circuit shuts down all the driver outputs when the chip junction temperature is increased to about 175C (typical). The thermal shutdown circuit is deactivated when the temperature drops to about 20C (typical). (6) Input pins (pins 4, 5, 12, and 13) These pins have characteristics negatively correlated to temperature. Give full consideration to the temperature effect when using the IC. 739 Motor driver ICs BA6845FS Electrical characteristic curves External dimensions (Units: mm) 740