SLOA312 December   2021 DRV8412 , DRV8424 , DRV8426 , DRV8428 , DRV8434 , DRV8436 , DRV8803 , DRV8804 , DRV8805 , DRV8806 , DRV8844 , DRV8847 , DRV8932 , DRV8935 , DRV8955

PRODUCTION DATA  

  1.   Trademarks
  2. 1Introduction
  3. 2Principle of Operation
    1. 2.1 Unipolar Stepper Motors
    2. 2.2 Bipolar Stepper Motors
  4. 3How to Drive Unipolar Stepper Motors with DRV8xxx Drivers
    1. 3.1 Driving Unipolar Motor with Four-channel Low-side Driver
    2. 3.2 Driving a Unipolar Motor with a Bipolar Driver
    3. 3.3 Driving Unipolar Motor with Four-channel Half-Bridge Driver
      1. 3.3.1 Driving in Full-step Mode
        1. 3.3.1.1 Full-step Mode with One Phase ON
        2. 3.3.1.2 Two Phases ON
      2. 3.3.2 Driving in Half-step Mode
      3. 3.3.3 Example Pseudocode
        1. 3.3.3.1 Code for Full-step with One Phase ON
        2. 3.3.3.2 Code for Full-step with Two Phase ON
        3. 3.3.3.3 Code for Half-step
  5. 4References

3.3 Driving Unipolar Motor with Four-channel Half-Bridge Driver

Another way to drive a unipolar motor is to use four-channel half-bridge drivers, such as the DRV8932, DRV8935, DRV8955, DRV8844, DRV8847, and DRV8412. These drivers all feature PWM input interface, and therefore can be operated such that an external controller turns on low-side MOSFETs in succession to drive a unipolar stepper motor. Table 3-3 summarizes the major features of these half-bridge drivers.

Table 3-3 Comparison among DRV8xxx Half-bridge Drivers
Driver DRV8847 DRV8932 DRV8935 DRV8955 DRV8412 DRV8844
Maximum Supply Voltage 18 V 33 V 33 V 48 V 52 V 60 V
LS MOSFETRDS(ON) 0.45 Ω 0.45 Ω 0.165 Ω 0.165 Ω 0.11 Ω 0.24 Ω
Independent Half-bridge Yes No No Yes Yes Yes
Package Options HTSSOP-16, QFN-16 HTSSOP-28, QFN-24 HTSSOP-28, QFN-24 HTSSOP-28, QFN-24 HTSSOP-44 HTSSOP-28
Maximum Continuous Output Current 1 A 1.5 A 2.5 A 2.5 A 3 A 2.5 A
Protection Features Overcurrent,Short circuit, Undervoltage, Overtemperature Overcurrent,Short circuit, Undervoltage, Overtemperature Overcurrent,Short circuit, Undervoltage, Overtemperature Overcurrent,Short circuit, Undervoltage, Overtemperature Overcurrent,Short circuit, Undervoltage, Overtemperature Overcurrent,Short circuit, Undervoltage, Overtemperature

In the following section, this approach is described in detail by showing how unipolar stepper motors can be driven by the DRV8935. A typical application schematic with the DRV8935 is shown in Figure 3-5.

GUID-FD2A0AE7-A8D4-422A-A187-335A3E4ED140-low.jpg Figure 3-5 Unipolar Stepper Schematic with DRV8935

The PWM inputs can be controlled to drive a unipolar stepper motor in full-step or half-step modes, as described in the following subsections.