DRV8802-Q1_15 Datasheet, PDF (15/26 Pages) Texas Instruments – DRV8802-Q1 Automotive DC Motor-Driver IC

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DRV8802-Q1
SLVSCI2A – JUNE 2014 – REVISED JUNE 2014
9 Power Supply Recommendations
The DRV8802-Q1 is designed to operate from an input voltage supply V_(VMx) range between 8.2 and 45 V. Two
0.1-µF ceramic capacitors rated for V_(VMx) 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.
9.1 Bulk Capacitance
Bulk capacitance sizing is an important factor in motor drive system design. It 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. You should size the bulk capacitance to meet acceptable
voltage ripple levels. The datasheet generally provides a recommended value but system level testing is required
to determine the appropriate sized bulk capacitor.
Power Supply
Parasitic Wire
Inductance
Motor Drive System
V_M
+
+
Motor
±
Driver
GND
Local
Bulk Capacitor
IC Bypass
Capacitor
Figure 10. Example Setup of Motor Drive System WIth External Power Supply
9.2 Power Supply and Logic Sequencing
No specific sequence exists for powering-up the DRV8802-Q1 device. Digital input signals can be present before
V_(VMx) is applied. After V_(VMx) is applied to the DRV8802-Q1 device, it begins operation based on the status of the
control pins.
10 Layout
10.1 Layout Guidelines
The VMA and VMB pins should be bypassed to GND using low-ESR ceramic bypass capacitors with a
recommended value of 0.1-μF rated for VM. This capacitor should be placed as close to the VMA and VMB pins
as possible with a thick trace or ground plane connection to the device GND pin. The VMA and VMB pins must
be bypassed to ground using an appropriate bulk capacitor. This component may be an electrolytic and should
be located close to the DRV8802-Q1. A low-ESR ceramic capacitor must be placed in between the CPL and
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