DRV8461SPWPR datasheet(101/117 Pages) TI

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8.2.2 Detailed Design Procedure

8.2.2.1 Stepper Motor Speed

The first step in configuring the DRV8461 requires the desired motor speed and microstepping level. If the target

application requires a constant speed, then a square wave with frequency ƒstep must be applied to the STEP pin.

If the target motor speed is too high, the motor does not spin. Make sure that the motor can support the target

speed. Use Equation 15 to calculate ƒstep for a desired motor speed (v), microstepping level (nm), and motor full

step angle (θstep)

step

v (rpm)

360 ( / rot)

VWHSV V

( / step) n

(steps / microstep)

60 (s / min)

(15)

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 7.5 rpm at 1/16 microstep mode. Using

Equation 15, ƒstep can be calculated as 400 Hz.

The microstepping level is set by the M0 and M1 pins or the MICROSTEP_MODE bits and can be any of the

settings listed in Table 7-5. Higher microstepping results in a smoother motor motion and less audible noise, but

requires a higher ƒstep to achieve the same motor speed.

8.2.3 Application Performance Plots

Ch 1 = Coil A current, Ch 5 = Coil B current, Ch 6 = AOUT1, Ch 7 = AOUT2

Figure 8-2. 1/16 microstepping at 400 pps with IFS = 3 A

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DRV8461

SLOSE98 – DECEMBER 2022

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