DRV8823_16 Datasheet, PDF (18/32 Pages) Texas Instruments – 4-Bridge Serial Interface Motor Driver

DRV8823
SLVS913E – JANUARY 2009 – REVISED JANUARY 2016
www.ti.com
Typical Application (continued)
8.2.1 Design Requirements
Table 5 shows the design parameters.
Table 5. Design Parameters
DESIGN PARAMETER
Supply voltage
Motor winding resistance
Motor full step angle
Target microstepping angle
Target motor speed
Target full-scale current
REFERENCE
V_M
R_L
θ_step
n_m
V
I_FS
8.2.2 Detailed Design Procedure
EXAMPLE VALUE
24 V
7.4 Ω/phase
1.8°/step
1/8 step
120 rpm
1A
8.2.2.1 Motor Voltage
The appropriate motor voltage will depend on the ratings of the motor selected and the desired torque. A higher
voltage shortens the current rise time in the coils of the stepper motor allowing a greater average torque. Using a
higher voltage also allows the motor to operate at a faster speed than a lower voltage.
8.2.3 Drive Current
The current path running to the motor starts from the supply VM, then goes through the high-side sourcing
NMOS power FET, moves through the inductive winding load of the motor, then through the low-side sinking
NMOS power FET, and finally going through the external sense resistor. Power dissipation losses in both NMOS
power FETs inside of the DRV8823 are shown in the following equation: Equation 2.
P = I² × (R_{DS (on)} × 2)
(2)
The DRV8823 has been measured to be capable of 1.5-A continuous current with the HTSSOP package at 25°C
on standard FR-4 PCBs. The max continuous current varies based on PCB design and the ambient temperature.
8.2.4 Application Curves
Figure 15. ½ Step Microstepping With Slow Decay
Figure 16. 1/8 Step Microstepping With Slow Decay
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