Introduction The AMIS?30421 is a micro-stepping stepper motor bridge controller for large current range bipolar applications. The chip interfaces via a SPI interface with an external controller in order to control 2 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. It uses a proprietary PWM algorithm for reliable current control. The AMIS?30421 contains a current translation table and takes the next micro-step 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 AMIS?30421 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. The AMIS?30421 is easy to use and ideally suited for 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.