Stepper Motor Reference Design

The stepper motor reference design exhibits the best way to use a microcontroller for motor functions, providing instruments for code improvement and {hardware} integration with parts.

Stepper motors are utilized in many alternative functions. They’re generally present in shopper workplace gear like printers, plotters, copiers, and scanners. In automotive programs, they’re used for digital throttle management, dashboard indicators, and local weather management. Stepper motors are additionally utilized in industrial gear, together with robotics, digital element handlers, testers, dispensers, and different manufacturing equipment. The stepper motor reference design from Silicon Labs exhibits the best way to use the C8051F301 microcontroller in high-performance stepper motor functions. It additionally serves as a platform for creating stepper motor codes. The firmware features a linear-velocity profiler with adjustable acceleration.

The Stepper motor reference design {hardware} consists of 4 sections. These are the microcontroller, energy electronics, voltage regulator, and serial interface. The microcontroller is housed in a compact 3 mm by 3 mm 11-lead microlead package deal (MLP), sufficiently small to be built-in into probably the most miniature motors. The C8051F30x household consists of 5 units with completely different choices. The ‘F300 and ‘F301 have a calibrated inside oscillator, correct to inside ±2% at check. This makes the inner oscillator appropriate for the UART with baud charges as much as 115.2 kbps. The reference design doesn’t use the 8-bit 500 ksps ADC within the ‘F300, so both the ‘F300 or the ‘F301 can be utilized, because the ‘F301 doesn’t have the ADC. The ADC on the F300 may very well be useful in some designs for monitoring the DC motor voltage, stepper motor present, or motor temperature.

The facility MOSFET chosen for the stepper motor reference design is the Fairchild FDS8926A. These small, low-on-resistance MOSFETs are available in an SO8 package deal. They had been chosen for his or her 30 V score, 3 V gate, and SO8 package deal. A most drain-to-source score of 30 V is required to drive the 12 V stepper motor, and the chosen MOSFET is suitable with a 3 V MCU. The FDS8926A has an on-resistance of 38 mΩ at 2.5 V, making it appropriate to deal with 2-3 A on this software.

The voltage regulator used is the LM2973-3.3, a 3.3 V low-dropout regulator in an SOT223 package deal. Its most steady enter voltage is 26 V. When deciding on a voltage regulator, it’s essential to contemplate the utmost open circuit voltage of the facility provide. The worst-case whole VDD present draw for the board is roughly 25 mA, which happens when each LEDs are on and the serial port runs at 115.2 kbps. Underneath this situation, the regulator will dissipate round 300 mW of energy with an enter voltage of 15 V.

Silicon Labs has examined this reference design. It comes with a invoice of supplies (BOM), schematics, meeting drawing, printed circuit board (PCB) structure, and extra. The corporate’s web site has extra information concerning the reference design. To learn extra about this reference design, click on right here.