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

3 Digital-to-Analog Converter Method

In some applications it is required for the VREF input to be modified in real time. In this case, fixing the analog voltage through a voltage divider is detrimental to the application. The optimal solution is to employ a DAC function which can be programmed to a target value as the application requires. The DAC can be a function internal to a microcontroller, or a stand alone block driven by any processor.

The DAC output can be connected directly to the VREF input, as shown on Figure 3-1. A 1000 pf capacitor to GND is recommended to filter out any DAC transition noise.

GUID-84F226A7-13C6-4F4D-BBFD-A2ECC9D504E9-low.gifFigure 3-1 A Microcontroller DAC Drives the DRV88xx VREF Input

Typical implementations requiring a DAC function are brushed DC motor driving with torque control, steppers requiring a holding torque different than running torque, and steppers being commutated through a high resolution micro-stepping lookup table.