DRV8848_15 Datasheet, PDF (18/28 Pages) Texas Instruments – DRV8848 Dual H-Bridge Motor Driver

DRV8848
SLLSEL7 – OCTOBER 2014
www.ti.com
10 Power Supply Recommendations
The DRV8848 is designed to operate from an input voltage supply (V_VM) range between 4 and 18 V. Place a 0.1-
µF ceramic capacitor rated for VM as close to the DRV8848 as possible. In addition, the user must include a bulk
capacitor of at least 10 µF on VM.
10.1 Bulk Capacitance Sizing
Bulk capacitance sizing is an important factor in motor drive system design. It depends on a variety of factors
including:
• Type of power supply
• Acceptable supply voltage ripple
• Parasitic inductance in the power supply wiring
• Type of motor (brushed DC, brushless DC, stepper)
• Motor startup current
• Motor braking method
The inductance between the power supply and motor drive system limits the rate that current can change from
the power supply. If the local bulk capacitance is too small, the system responds to excessive current demands
or dumps from the motor with a change in voltage. Size the bulk capacitance to meet acceptable voltage ripple
levels.
The data sheet provides a recommended minimum value, but system-level testing is required to determine the
appropriate-sized bulk capacitor.
Power Supply
Parasitic Wire
Inductance
Motor Drive System
VM
+
+
Motor
±
Driver
GND
Local
Bulk Capacitor
IC Bypass
Capacitor
Figure 13. Setup of Motor Drive System With External Power Supply
18
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