DRV8834 Datasheet, PDF (12/30 Pages) Texas Instruments – DUAL BRIDGE STEPPER OR DC MOTOR DRIVER

DRV8834
SLVSB19A – FEBRUARY 2012 – REVISED MARCH 2012
www.ti.com
Phase/Enable Mode
In phase/enable mode, the xPHASE input pins control the direction of current flow through each H-bridge. This
sets the direction of rotation of a DC motor, or the direction of the current flow in a stepper motor winding. Driving
the xENBL input pins active high enables the H-bridge outputs. This can be used as PWM speed control of a DC
motor, or to enable/disable the current in a stepper motor.
In phase/enable mode, the M1 input pin controls the state of the H-bridges when xENBL = 0. If M1 is high, the
outputs are disabled (high impedance) when xENBL = 0; this corresponds to asynchronous fast decay mode,
and is usually used in stepper motor applications to command a "zero current" state. If M1 is low, then the
outputs are both driven low; this corresponds to slow decay or brake mode, and is usually used when controlling
the speed of a DC motor by PWMing the xENBL pin.
Table 3. H-Bridge Control Using Phase/Enable Mode
M1
xENBL
xPHASE
xOUT1
xOUT2
1
0
X
Z
Z
0
0
X
0
0
X
1
0
L
H
X
1
1
H
L
Indexer Mode
To allow a simple step and direction interface to control stepper motors, the DRV8834 contains a microstepping
indexer. The indexer controls the state of the H-bridges automatically. Whenever there's a rising edge at the
STEP input, the indexer moves to the next step, according to the direction set by the DIR pin.
The nENBL pin is used to disable the output stage in indexer mode. When nENBL = 1, the indexer inputs are still
active and will respond to the STEP and DIR input pins; only the output stage is disabled.
The indexer logic in the DRV8834 allows a number of different stepping configurations. The M0 and M1 pins are
used to configure the stepping format as shown in Table 4.
Table 4. Stepping Format
M1
M0
STEP MODE
0
0
Full step (2-phase excitation)
0
1
1/2 step (1-2 phase excitation)
0
Z
1/4 step (W1-2 phase excitation)
1
0
8 microsteps/step
1
1
16 microsteps/step
1
Z
32 microsteps/step
Note that the M0 pin is a tri-level input. It can be driven logic low, logic high, or high-impedance (Z).
The M0 and M1 pins can be statically configured by connecting to VINT, GND, or left open, or can be driven with
standard tri-state microcontroller I/O port pins. Their state is latched at each rising edge of the STEP input.
The step mode may be changed on-the-fly while the motor is moving. The indexer will advance to the next valid
state for the new M0/M1 setting at the next rising edge of STEP.
The home state is 45°. This state is entered after power-up, after exiting undervoltage lockout, or after exiting
sleep mode. This is shown in Table 5 by cells shaded yellow.
The following table shows the relative current and step directions for different step mode settings. At each rising
edge of the STEP input, the indexer travels to the next state in the table. The direction is shown with the DIR pin
high; if the DIR pin is low the sequence is reversed. Positive current is defined as xOUT1 = positive with respect
to xOUT2.
12
Submit Documentation Feedback
Product Folder Link(s): DRV8834
Copyright © 2012, Texas Instruments Incorporated