DRV8885

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SLVSD39 – OCTOBER 2015

7 Detailed Description

7.1 Overview

The DRV8885 is an integrated motor driver solution for bipolar stepper motors. The device integrates two NMOS

H-bridges, integrated current sense and regulation circuitry, and a microstepping indexer. The DRV8885 can be

powered with a supply voltage between 8 and 37 V, and is capable of providing an output current up 2.1-A peak,

1.5-A full-scale, or 1.0-A rms. Actual full-scale and rms current will depend on ambient temperature, supply

voltage, and PCB ground plane size.

The DRV8885 integrates current sense functionality, which eliminates the need for high-power external sense

resistors. This integration does not dissipate the external sense resistor power, because the current sense

functionality is not implemented using a resistor-based architecture. This functionality helps improve component

cost, board size, PCB layout, and system power consumption.

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

capable of full step and half step as well as microstepping to 1/4, 1/8, and 1/16. In addition to the standard half

stepping mode, a non-circular 1/2-stepping mode is available for increased torque output at higher motor rpm.

The current regulation is configurable with several decay modes of operation. The decay mode can be selected

as a fixed slow, slow/mixed, or mixed decay. The slow/mixed decay mode uses slow decay on increasing steps

and mixed decay on decreasing steps.

An adaptive blanking time feature automatically scales the minimum drive time with output current. This helps

alleviate zero-crossing distortion by limiting the drive time at low-current steps.

A torque DAC feature allows the controller to scale the output current without needing to scale the reference

resistor. The torque DAC is accessed using a digital input pin. This allows the controller to save power by

decreasing the current consumption when not high current is not required.

A low-power sleep mode is included which allows the system to save power when not driving the motor.

Copyright © 2015, Texas Instruments Incorporated

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Product Folder Links: DRV8885