DRV8434SPWPR datasheet(52/73 Pages) TI

52 / 73 page

step

v (rpm)

360 ( / rot)

VWHSV V

( / step) n

(steps / microstep)

60 (s / min)

(2)

The value of θstep can be found in the stepper motor data sheet, or written on the motor. For example, the motor

in this application is required to rotate at 1.8°/step for a target of 18.75 rpm at 1/8 microstep mode. Using

Equation 2, ƒstep can be calculated as 500 Hz.

The microstepping level is set by the MICROSTEP_MODE bits. Higher microstepping results in a smoother

motor motion and less audible noise, but requires a higher ƒstep to achieve the same motor speed.

8.2.2.2 Current Regulation

In a stepper motor, the full-scale current (IFS) is the maximum current driven through either winding. This quantity

depends on the VREF voltage and the TRQ_DAC setting, as shown in Equation 3.

The maximum allowable voltage on the VREF pin is 3.3 V. DVDD can be used to provide VREF through

aresistor divider.

During stepping, IFS defines the current chopping threshold (ITRIP) for the maximum current step.

(3)

8.2.2.3 Decay Mode

The DRV8434A operates with smart tune ripple control decay mode. When a motor winding current has hit the

current chopping threshold (ITRIP), the DRV8434A places the winding in slow decay.

8.2.2.4 Application Curves

Figure 8-3. 1/8 Microstepping With smart tune

Ripple Control Decay

Figure 8-4. 1/8 Microstepping With smart tune

Dynamic Decay

Figure 8-5. 1/32 Microstepping With smart tune

Ripple Control Decay

Figure 8-6. 1/32 Microstepping With smart tune

Dynamic Decay

DRV8434S

SLOSE70 – DECEMBER 2020

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DRV8434SPWPR Datasheet(PDF) 52 Page - Texas Instruments