DRV8846_15 Datasheet, PDF (11/35 Pages) Texas Instruments – DRV8846 Dual H-Bridge Stepper Motor Driver

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DRV8846
SLLSEK2 – JUNE 2014
8.3 Feature Description
8.3.1 PWM Motor Drivers
DRV8846 contains two identical H-bridge motor drivers with current-control PWM circuitry. Figure 6 shows a
block diagram of the circuitry.
OCP
VM
VM
STEP
DIR
Indexer
VREF
I1
I0
Internal
reference
To other
channel
To other
channel
PWM
3-
level
Input
buffer
DAC
3
From Indexer
SIN
5
DAC
Pre-
drive
OCP
±
A = 6.6
+
xOUT1
xOUT2
Step
Motor
xISEN
Optional
Figure 6. PWM Motor Driver Circuitry
8.3.2 Micro-Stepping Indexer
To allow a simple step and direction interface to control stepper motors, the DRV8846 contains a microstepping
indexer. The indexer controls the state of the H-bridges automatically. When the correct transition is applied at
the STEP input, the indexer moves to the next step, according to the direction set by the DIR pin. In 1/8, 1/16,
and 1/32 step modes, both the rising and falling edges of the STEP input may be used to advance the indexer,
depending on the M0 / M1 setting.
The nENBL pin disables the output stage in indexer mode. When nENBL = 0, the indexer inputs are still active
and respond to the STEP and DIR input pins; only the output stage is disabled.
The indexer logic in the DRV8846 allows a number of different stepping configurations. The M0 and M1 pins
configure the stepping format (see Table 2).
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