DRV8801A-Q1_15 Datasheet, PDF (15/24 Pages) Texas Instruments – DRV8801A-Q1 DMOS Full-Bridge Motor Drivers

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DRV8801A-Q1
SLVSC79A – JUNE 2014 – REVISED SEPTEMBER 2014
9 Power Supply Recommendations
The DRV8801A-Q1 device is designed to operate from an input-voltage supply (V_BB) range between 6.5 V and
36 V. One 0.1-µF ceramic capacitor rated for V_BB must be placed as close as possible to the V_BB pin. In addition
to the local decoupling caps, additional bulk capacitance is required and must be sized accordingly to the
application requirements.
9.1 Bulk Capacitance
Bulk capacitance sizing is an important factor in motor drive system design. This sizing is dependent 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 will limit the rate current can change from the
power supply. If the local bulk capacitance is too small, the system will respond 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 generally provides a recommended value but system-level testing is required to determine the
appropriate sized bulk capacitor.
Parasitic Wire
Inductance
External Power Supply
Motor Drive System
V_BB
+
±
Power Supply
Bulk Cap
Local
Bulk Cap
GND
Local
Filter Cap
Motor
Driver
Figure 9. Bulk Capacitance
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