DRV8824_14 Datasheet, PDF (22/36 Pages) Texas Instruments – DRV8824 Stepper Motor Controller IC

DRV8824
SLVSA06I – OCTOBER 2009 – REVISED JUNE 2014
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10 Power Supply Recommendations
The DRV8824 is designed to operate from an input voltage supply (VM) range between 8.2 and 45 V. Two 0.01-
µF ceramic capacitors rated for VM must be placed as close as possible to the VMA and VMB pins respectively
(one on each pin). In addition to the local decoupling caps, additional bulk capacitance is required and must be
sized accordingly to the application requirements.
10.1 Bulk Capacitance
Local bulk capacitance sizing is a critical factor in proper motor drive system design. It is dependent on a variety
of factors including the type of power supply, inductance in the power supply wiring, type of motor, load
demands/dumps of the motor, acceptable voltage ripple, and various other factors.
Although power supplies often contain large amounts of bulk capacitance, this is often separated from the local
motor drive system by parasitic inductance in the power supply wiring. The parasitic inductance will limit the rate
current can change from the power supply and force the system to demand or dump current from or to another
source with a lower inductance path. This source is often the local bulk capacitance located near the motor drive
system. The magnitude and rate of the motor current demand or dump and acceptable voltage ripple will
determine how large this bulk capacitance needs to be.
The data sheet provides a recommended bulk capacitance value, but system-level testing is required to
determine the appropriate sized capacitor for specific applications. A smaller filter capacitor (optional) may also
be added to remove higher frequency noise from the power supply lines that may pass the bulk capacitance.
Parasitic Wire
Inductance
External Power Supply
Motor Drive System
VM
+
±
Power Supply
Bulk Capacitor
Local
Bulk Cap
GND
Local
Filter Cap
Motor
Driver
Figure 11. Example Setup of Motor Drive System With External Power Supply
10.2 Power Supply and Logic Sequencing
There is no specific sequence for powering-up the DRV8824. It is okay for digital input signals to be present
before VM is applied. After VM is applied to the DRV8824, it begins operation based on the status of the control
pins.
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