ROHM provides more than 220 motor driver ICs, which have proven themselves time after time. The motor types covered by these driver ICs run the gamut, including brushed DC motors, stepping motors, single-phase brushless DC motors, and 3-phase brushless DC motors (including high-voltage models). The ROHM lineup of motor driver ICs affords high efficiency and reliability with wide ranges of voltages, currents, and package types, and pin-compatible models are also provided.
Among these products, there are over 50 types of brushed DC motor driver ICs. The brushed DC motor driver ICs manufactured by ROHM have an H bridge configuration incorporating MOSFETs. Driving with DC voltages or with PWM is possible, and in addition to forward and reverse modes, standby modes and braking modes are also provided. Driver ICs also provide power-saving functions, shoot-through-current prevention functions, and various protection functions to address anomalous states such as overcurrents, overvoltages, overtemperature, undervoltages, line faults, ground faults, and load short-circuits, and also feature VREF control functions, current-limiting functions, and support for high-speed driving.
The main functions and features are explained below, taking as examples the standard BD62xx series. The following is a truth table for the BD62xx series.
In all, nine modes are provided. FIN and RIN are respectively positive and negative control inputs. Modes a to d are basic modes. The H bridge switch states and current paths are shown below.
In standby mode, everything, including output power transistors and internal control circuitry, is turned off, so that current consumption can be reduced. The OUT pin is at high impedance. Braking mode is used to quickly stop a motor that is rotating. It differs from standby mode in that the internal control circuitry is operating, and so when there is a need to reduce current consumption in an idling state, standby mode should be used.
In modes e, f, g, and h, by inputting a PWM signal to FIN pin or RIN pin and using PWM control to control the motor (modes b and c use DC driving), highly efficient driving is possible. Forward/reverse settings and the combination of PWM operation or fixed logic (H side/L side) for the output can be selected.
Modes i and j are VREF control modes.
VREF Control Functions
In addition to the standard overcurrent protection function, some of the ICs are equipped with a current-limiting function. The current limit value can be set through a resistor for output current detection and the voltage applied to the VREF pin. Using this function, it is possible to limit e.g. the inrush current at motor startup.
Support for High-Speed Driving
The following ICs enable switching in four stages of the turn-on and turn-off times. By shortening the turn-on and turn-off times, the H bridge operating frequency can be raised, supporting applications in which high-speed driving is necessary, such as digital cameras, multivision cameras, paper currency counting devices, mobile equipment, home appliances, and amusement devices.