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

2 Resistive Network Voltage Divider Method

The simplest form to derive the external analog reference voltage is by dividing down a higher rail voltage. For example, the logic voltage could be set to be VIN equal to 3.3 V or 5 V and a voltage divider, as depicted on Figure 2-1(a), would step this rail down to the target reference voltage.

GUID-15967599-AF0D-46C6-9692-52F63B17643B-low.gifFigure 2-1 A voltage divider can be used to set the VREF parameter.

If the application requires manual current tuning, a potentiometer can be used instead of two fixed resistors. VREF is a high impedance input, so the total resistive value for the potentiometer is very flexible.

Figure 2-1(b) portrays how on some of the DRV88xx devices, a 3.3 V rail (V3P3OUT) is provided, which can be used as the voltage rail to drive the voltage divider and derive the target reference voltage. In these implementations, external device count is reduced as an external regulator is not required. User must refer to the respective device’s datasheet to determine maximum available current from this output. Total resistance sourced from this output must be selected so maximum current drawn is not exceeded.