Introduction
The AMIS−30521/NCV70521 is a micro−stepping stepper motor driver for bipolar stepper motors. The chip is connected through I/O pins and a SPI interface with an external microcontroller. The AMIS−30521/NCV70521 contains a current−translation table. It 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. It is using a proprietary PWM algorithm for reliable current control.

FEATUREs
• Dual H−Bridge for 2 Phase Stepper Motors
• Programmable Peak−Current Up to 1.2 A Continuous (1.5 A Short Time), Using a 5−Bit Current DAC
• On−Chip Current Translator
• SPI Interface
• Speed and Load−Angle Output
• 7 Step Modes from Full Step−up to 32 Micro−Steps
• Fully Integrated Current−Sense
• PWM Current Control with Automatic Selection of Fast and Slow Decay
• Low EMC PWM with Selectable Voltage Slopes
• Active Flyback Diodes
• Full Output Protection and Diagnosis
• Thermal Warning and Shutdown
• Digital IO’s Compatible with 5 V and 3.3 V Microcontrollers
• NCV Prefix for Automotive and Other Applications Requiring Site and Control Changes
• These are Pb−Free Devices*