Toshiba is the world's 5^th largest semiconductor company¹ and a leading, worldwide supplier of motor driver and motor controller technology to the industry's top companies in office automation, industrial equipment, consumer and home appliance and battery-powered applications. Toshiba develops long-term, strategic relationships with its customers by providing motor driver products that are exceptionally versatile, power efficient and robust.

Toshiba develops its motor controller and driver ICs in its leading-edge BiCMOS and BiCD (Bipolar+CMOS+DMOS) processes. The BiCD process combines the analog advantages of bipolar devices with the digital and low-power consumption benefits of MOSFETs, as well as the high-power capabilities of DMOS devices.

Toshiba has added six new next-generation stepping motor control drivers to its broad portfolio of products. The motor control drivers are designed using the Toshiba BiCD 130nm mixed-signal process technology, providing excellent Ron per unit area, to achieve highly integrated, low-power devices with the industry's highest voltage and current combination, (Parts TB6600HG and TB67H302HG)² and compact footprints (Parts TB67S213FTAG, TB67S215FTAG, TB62261FTAG and TB62262FTAG). These devices are well suited for a variety of applications such as printers, ATM, robotics, process control machines, and medical equipment.

Most modern gadgets, from small handheld electronic devices like cameras to larger machines such as printers, washing machines and dishwashers, have electronic motors. The intricate movements of these electronic motors can be controlled by microcontrollers (MCUs) or microcomputers.

When using MCUs for motor control, additional components are necessary since most MCUs can't pass enough current or voltage to spin a motor. Also, a motor tends to be electrically noisy. It creates spikes that can slam power back into the control lines when the motor direction or speed is changed. This noise can damage the MCU if it does not have adequate isolation. Furthermore, some motor types, such as stepping motors, would not run at all without a fast sequence of power pulses. Generating these pulses uses up a considerable amount of the MCU's capabilities that would be much better utilized for higher-level control.

To unburden the MCU and free it up to manage higher-level control functions, Toshiba has developed motor controller devices and motor drivers (MCDs). These devices supply motors with current, drive the motor with the necessary V and I pulses to ensure a smooth rotation and isolate other ICs from electrical problems. These circuits are designed as completely separate chips and are reusable from project to project.

When a motor controller device is used, external circuitry is often needed to transform the low-power signals of the controller into high-power pulses to drive the motor. Toshiba has created a line of motor drivers that combine a low-power controller and high-power driver. The low-power controller generates high-precision pulses that are needed to drive motors like stepping motors or BLDCs. These pulses enable precise forward/reverse rotation as well as other benefits such as overheat protection. The high-power driver stage, on the other hand, insulates the low-power controller part from the motor. These devices can drive a motor with a minimum of external discrete devices.

Toshiba's latest generation of drivers are designed mostly using the Toshiba proprietary BiCD process that combines the advantages of low-power bipolar and CMOS devices with superior, high-power DMOS capabilities to drive a motor. These motor drivers can switch easily between clockwise and counter-clockwise (CW/CCW) operation of the motor and regulate the motor speed using pulse width modulation (PWM).

Output of some of the Toshiba motor drivers (e.g. TB6559) can be adjusted by either input of a constant current or by an externally applied PWM signal. The PWM signal would then be generated for example by a microcontroller.

PWM is a method used to change the drive power provided to the motor from the MCD by changing the power pulse width that is sent to the motor, while keeping the pulse frequency constant (Figure 1). Another approach is to keep the pulse width constant and to change the pulse frequency, which is known as pulse frequency modulation (PFM).

Figure 1: Chopper method to obtain a PWM signal

When using PWM, averaging is achieved by setting the pulse frequency high enough (~100kHz), so that the inertia of the system leads to the averaging of the transmitted power. Changing the pulse width, or duty cycle, changes Figure 1: Chopper method to obtain a PWM signal the drive power. The extremes are 0% duty cycle, with no high pulse and 100% duty cycle with one continuous pulse that leads to a constant high signal. The medium value is a 50% duty cycle, with half period high and half period low, which leads to half of the supply power.

Generally PWM can be used either as a low-power control signal to drive the high-power stage, which drives and supplies the actual motor or the driver output to the motor is a PWM drive (chopper-type) and the averaging is achieved by the inertia of the motor itself. Toshiba offers MCDs that employ PWM and drivers that use high-power DMOS devices, implemented as H switches (or H-bridges), to drive and supply the motor.

A very popular circuit for driving DC motors is called an H-bridge (also called full-bridge), since it looks like the capital letter 'H' on classic schematics. With an H-bridge circuit the motor can be driven forward or backward at any speed using a completely independent power source.

An H-bridge design can be simple for prototyping or intricate for added protection and isolation. An H-bridge can be implemented with various kinds of components (bipolar transistors, MOSFETs and/or power MOSFETs). Toshiba's next-generation of motor driver ICs uses high-power DMOS devices to implement H-bridges.

Most motor controllers are not really supposed to be used independently to drive a motor. If you find the chip gets very hot and the motor doesn't spin, barely spins or stalls when loaded then you need to add a power stage between the motor controller and motor. Toshiba offers motor drivers that have a power output stage with DMOS transistors already implemented in the same packaging with the motor controller.

The purpose of a motor driver is to control a motor and the purpose of the motor is to convert electrical energy into motion. The motor driver's performance can be measured by how much power it delivers to the motor versus how much is wasted in the motor driver electronics.

The amount of power delivered to the motor is crucial to the application. The amount of motor power directly impacts the torque and speed (RPMs). Furthermore, in battery-powered applications it is important to avoid wasting electricity on the H-bridge components.

A very simple technique for approximating the efficiency of a motor H-bridge is to measure the battery voltage with a multimeter while simultaneously measuring the voltage on the motor wires with another multimeter. For example, if the battery measures 5 volts (during usage) and the motor voltage measures 2.5 volts, then only half of the voltage is reaching the motor!

The Toshiba motor drivers combine standalone solutions to drive DC motors with versatile and easy implementation in a variety of different designs. Additionally, the Toshiba motor controllers capture many error states such as overheat protection without the need for additional software or hardware solutions.

The Toshiba motor controller/driver are designed to reduce the need for external parts to a minimum and to free all MCU capabilities in your design for higher-level control.