DRV8821_16 Datasheet, PDF (9/32 Pages) Texas Instruments – Dual Stepper Motor Controller and Driver

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7 Detailed Description
DRV8821
SLVS912J – JANUARY 2009 – REVISED JANUARY 2016
7.1 Overview
The DRV8821 is a dual stepper motor driver solution for applications that require independent control of two
different motors. The device integrates four NMOS H-bridges, a microstepping indexer, and various fault
protection features. The DRV8821 can be powered with a supply voltage between 8 and 32 V, and is capable of
providing an output current up to 1.5-A full scale. Actual full-scale current will depend on ambient temperature,
supply voltage, and PCB ground size.
A simple STEP/DIR interface allows easy interfacing to the controller circuit. The internal indexer is able to
execute high-accuracy microstepping without requiring the processor to control the current level. The indexer is
cable of full step and half step as well as microstepping to 1/4 and 1/8.
The current regulation is configurable with two different decay modes; slow decay and mixed decay. The mixed
decay mode uses slow decay on increasing current steps and mixed decay on decreasing current steps, while
slow decay mode will always use slow decay regardless increasing or decreasing steps.
The gate drive to each FET in all four H-Bridges is controlled to prevent any cross-conduction (shoot through
current) during transitions.
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