SLOA170B July   2012  – January 2021 DRV8242-Q1 , DRV8412 , DRV8424 , DRV8424E , DRV8425 , DRV8425E , DRV8426 , DRV8426E , DRV8428 , DRV8428E , DRV8434 , DRV8434E , DRV8436 , DRV8436E , DRV8701 , DRV8702-Q1 , DRV8702D-Q1 , DRV8703-Q1 , DRV8703D-Q1 , DRV8705-Q1 , DRV8706-Q1 , DRV8800 , DRV8801 , DRV8802 , DRV8802-Q1 , DRV8811 , DRV8812 , DRV8813 , DRV8814 , DRV8818 , DRV8821 , DRV8823 , DRV8823-Q1 , DRV8824 , DRV8824-Q1 , DRV8825 , DRV8828 , DRV8829 , DRV8832 , DRV8832-Q1 , DRV8833 , DRV8834 , DRV8840 , DRV8841 , DRV8842 , DRV8843 , DRV8844 , DRV8846 , DRV8848 , DRV8870 , DRV8874 , DRV8874-Q1 , DRV8876 , DRV8876-Q1 , DRV8880 , DRV8881 , DRV8885 , DRV8886 , DRV8889-Q1 , DRV8899-Q1 , DRV8935 , DRV8955

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 The Current Regulation Engine
    2. 1.2 Design Criteria
  3. 2Resistive Network Voltage Divider Method
    1. 2.1 GPIO Driven Voltage Divider
  4. 3Digital-to-Analog Converter Method
  5. 4PWM to RC Filter Method
  6. 5Changeable Holding Current Circuit
  7. 6Devices With Internal Reference Voltage
  8. 7Revision History

1 Introduction

Controlling current magnitude across an inductive load allows us to control the application’s torque. In applications driving inductive loads such as brushed DC motors, it may be required to limit the current during startup or during stalling conditions. On applications involving stepper motors designed with a very low winding resistance, controlling current is of paramount importance during all segments of the motion control profile.

When driving a stepper motor, regulating the current can work to the user’s advantage in two ways. If in full step commutation, controlling the maximum current level transfers into motor’s shaft torque control. With this implementation, the system is tuned to use only the necessary amount of current, decreasing motor vibrations. However, by adding different current levels into a full step, by modulating the current regulation engine’s input, micro steps can be induced. Such implementation reduces vibrations and audible noise further.

A good portion of the DRV88xx family of brushed DC and stepper motor drivers will contain a block offering current regulation which can be used to control the amount of current sourced into the aforementioned inductive loads. On this application note we detail some of the mechanisms available to program said current magnitude.