Two-phase microstepping motor driver features efficient unipolar design

Allegro MicroSystems Inc. announced a new unipolar two-phase constant-current mode motor driver IC, the SI-7321M, which features an efficient unipolar driver design for full- and half-step operation, and 1/4 , 1/8 , and 1/16 microstepping.

The clock-in type input interface allows simplified control logic, with the flexibility of sequencer timing using either rising Clock edge only or both rising and falling edges. Additional flexibility is provided by user-configurable blanking time, and load circuit short or open protection (patent pending). Along with inputs for built-in sense current detection, these features minimize power losses. This new motor driver is targeted at the office automation and industrial equipment markets.

The chip is manufactured and developed by Sanken Electric Co. Ltd. in Japan.

Key highlights:

• Power supply voltage, VBB , 46 V maximum, 10 to 44 V normal operating range
• 18.6 × 9.9 mm package footprint
• Logic supply voltage, VDD , 3.3 to 5.5 V
• Maximum output current: 1.5 A
• Four NMOS output MOSFETs, R DS(on) = 0.25 Ω typical
• Built-in sequencer
• Simplified clock-in stepping control
• Full- and half-stepping and 1/4 , 1/8 , and 1/16 microstepping
• Surface mount type 44-pin molded package for automatic assembly and low profile
• Self-excitation PWM current control with fixed off-time
• Microstepping off-time adjusted automatically by step reference current ratio
• Built-in synchronous rectifying circuit reduces losses at PWM switch-off
• Synchronous PWM chopping function prevents motor noise in Hold mode
• Built-in current sensing for each phase, set externally
• Dual sleep modes reduce IC input current in stand-by state
• Built-in protection against motor coil opens and shorts
• User-configurable operation options, set by external logic input:
  • Blanking time: 1.8 μs or 3.6 μs
  • Sequencer timing on Clock input rising (POS) edge or both rising and falling (POS/NEG) edges
  • Protection features enable or disable

Pricing: $5.90 in quantities of 1,000.

Availability: 12 week lead-time to market..

Datasheet: Click here.