Toshiba Electronic Devices & Storage Corporation Announces New Line-up of Stepping Motor Driver ICs with Anti-Stall Feedback Architecture

Avoiding stalls in stepping motor operation is the highest priority in securing stability and precise control, and is achieved by providing additional current that gives motors an operating torque margin. However, although it prevents stalls, the additional current decreases efficiency and generates heat. Complicated adjustments involving monitoring torque in real time with additional sensors and microcontrollers, and controlling the motor current are required to improve efficiency, reduce heat generation and prevent stalls.

The new products follow “TB67S289FTG,” the first stepping motor to incorporate original anti-stall active gain control (AGC^[2]). TB67S249FTG supports an industry-leading^[3] large drive current of 4.5A, 1.5 times that of TB67S289FTG. TB67S279FTG, with a current rating of 2A, delivers excellent cost performance compared with TB67S249FTG. All three products are compatible in packages, pin alignments and functions, allowing easy replacement among them. They enable optimal selection according to their applications, driving conditions, and purpose of use.

Like TB67S289FTG, TB67S249FTG and TB67S279FTG can also monitor motor operation and torque without an additional MCU, and optimize motor control and efficiency by applying AGC. They prevent motor stalls and automatically optimize motor current depending on the torque needed, reducing motor power consumption by up to 80%, compared with other solutions. They realize significant improvements in efficiency and heat generation without relying on on-resistance.

Further efficiencies can also be achieved when these stepping motor drivers are supported by advanced current detection system (ACDS^[4]), the innovative sense-resistor-free current monitor and control system, which allows more free space and uses fewer external components on the PCB.

The application of advanced automation systems, including ACG, achieves a series of products offering high performance motor control with a low component count. TDSC positions the new series as its flagship line of stepping motor drives, and will continue to expand the line-up.

1. Anti-stall and high efficiency

The new AGC motor control architecture improves motor efficiency and reduces heat generation. ACDS sense-resistor-less current control reduces PCB space requirements. Moreover, high-resolution 1/32 step (max.) motor control contributes to suppression of noise and vibration.

2. Lower heat generation

Heat generation is reduced by low on-resistance (TB67S249FTG: 0.33 Ω, TB67S279FTG: 0.60 Ω (upper + lower: typ.)).

3. Small package and pin compatible among series products

Packaging in a small QFN package allows customers to reduce heat problems and simplify set and module design patterns for heat dissipation. It will also realize affordable solutions in terms of space and cost. Moreover, TB67S289FTG, TB67S279FTG, and TB67S249FTG are compatible in packages and pins, allowing optimal component selection and replacement according to a usage environment.

4. Built-in error detection circuits

A motor load open detection function is now incorporated, in addition to thermal shutdown, over-current shutdown, and under voltage lock out. Error status can be flagged to external devices by an error flag function.

Notes:

[1] Motor stall: When motor rotation deviates from the control signal, stalling occurs and the motor stops rotating.

[2] AGC: A motor control architecture that automatically optimizes motor current to torque while preventing motor stalls.

[3] As of September 14, 2017, Toshiba Electronic Devices & Storage Corporation survey.

[4] ACDS: A motor control architecture that does not require an external sensing resistor to monitor the motor current.