Called Power Step 2 Click, the board “is based on the powerSTEP01, a 1/128 microstepping controller from STMicroelectronics that integrates eight n-channel mosfets with ultra-low Rds(on)”, according to Mikroe. “It features a 5MHz SPI interface, multiple safety protections, and additional control pins for function including step clock input and motor initialisation.”
Although the IC can handle 10Arms continuously, current handling through the Click board depends on heatsinking.
“With this size of Click board and a four-layer PCB, I would say that continuous drive current would be around 5A maximum,” the board’s designer told Electronics Weekly. “This can be improved by mounting a heatsink with the thermal paste directly onto the main IC, or increasing number of PCB layer, increasing board size, or for example using a Cooler Click board.” The latter is physically-compatible fan board.
Rds(on) of one low-side and one high-side output mosfet typically add up to 16mΩ. Mikroe told Electronics Weekly.
The IC has sine-wave generators to deliver up to 128 micro-steps per step and has a comprehensive set of features including a 22bit counter that deduces position by incrementing with steps in one direction and decrementing in the other. This can be set to zero to produce a nominal ‘home’ position for certain commands.
As well as simple step-direction commands, control features include constant speed commands (Run, GoUntil, ReleaseSW), absolute positioning commands (GoTo, GoTo_Dir, GoHome, GoMark), and various stops (SoftStop, HardStop, SoftHiz, HardHiz).
Acceleration, deceleration, maximum speed and minimum speed can be programmed in, and a threshold can be set so that the driver automatically moves to full-step mode at high speed before dropping back into micro-stepping when velocity reduces. This mode switch occurs at an electrical position multiple of π/4.
Applications are envisaged in robotics and automation, for example antenna and camera positioning.
Find the stepper motor Click board’s web page here, and the IC data sheet on thei Mikroe web page. The company also sells 10 x 10 x 7mm and 9 x 9 x5mm stick-on heatsinks.
Late last year, Moon’s Industries introduced a range of unusual stepper motors with large holes though the middle of the shaft.
