ON Semiconductor AMIS-30421 Micro-Stepping Stepper Motor Bridge Controller

The AMIS−30421 is a microstepping stepper motor bridge controller for large current range bipolar applications. The chip interfaces via an SPI interface with an external controller in order to control two external power NMOS H-bridges. It has an on-chip voltage regulator, current sensing, self-adapting PWM controller and pre-driver with smart slope control switching, allowing the part to be EMC compliant with industrial and automotive applications.

The product uses a proprietary PWM algorithm for reliable current control. It also contains a current translation table and takes the next microstep depending on the clock signal on the NXT input pin and the status of the DIR (direction) register or input pin. The chip provides a so-called Speed and Load Angle output. This allows the creation of stall detection algorithms and control loops based on load angle to adjust torque and speed.

The controller is implemented in a mature technology, enabling fast high-voltage analog circuitry and multiple digital functionalities on the same chip. The chip is fully compatible with automotive voltage requirements. It is easy to use and ideally suited to large current stepper motor applications in the automotive, industrial, medical and marine environment. With the on-chip voltage regulator it further reduces the BOM for mechatronic stepper applications.

The product features dual H-Bridge pre-drivers for 2-phase stepper motors; programmable current via SPI; on-chip current translator, SPI interface; speed and load angle output; eight step modes from full step up to 64 microsteps; current sensing via two external sense resistors; and has PWM current control with automatic selection of fast and slow decay.

It is compatible with 3.3 V microcontrollers and has an integrated 3.3 V regulator to supply an external microcontroller with an integrated reset function. It  is Pb free and is RoHS compliant.