DRV8801A-Q1_15 Datasheet, PDF (16/24 Pages) Texas Instruments – DRV8801A-Q1 DMOS Full-Bridge Motor Drivers

DRV8801A-Q1
SLVSC79A – JUNE 2014 – REVISED SEPTEMBER 2014
10 Layout
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10.1 Layout Guidelines
The printed circuit board (PCB) should use a heavy ground plane. For optimum electrical and thermal
performance, the DRV8801A-Q1 device must be soldered directly onto the board. On the bottom side of the
DRV8801A-Q1 device is a thermal pad, which provides a path for enhanced thermal dissipation. The thermal pad
should be soldered directly to an exposed surface on the PCB. Thermal vias are used to transfer heat to other
layers of the PCB. For more information on this technique, see the application report, PowerPAD™ Thermally
Enhanced Package, SLMA002.
The load supply pin, V_BB, should be decoupled with an electrolytic capacitor (typically 100 μF) in parallel with a
ceramic capacitor placed as close as possible to the device. In order to minimize lead inductance, the ceramic
capacitors between the VCP and V_BB pins, connected to the REG pin, and the capacitors between the CP1 and
CP2 pins should be as close to the pins of the device as possible.
10.2 Layout Example
GND
GND
OUTA
OUTB
R_(SENSE)
MODE2 ⁵
OUTA ⁶
SENSE ⁷
V_BB ⁸
GND
(PPAD)
0.1 µF
16 _MODE1
15 _nFAULT
14 _VPROPI
13 _VCP
0.1 µF
V_BB
0.1 µF
100 µF
GND
Figure 10. DRV8801A-Q1 Layout
10.3 Power Dissipation
First-order approximation of power dissipation in the DRV8801A-Q1 device can be calculated by examining the
power dissipation in the full-bridge during each of the operation modes. The DRV8801A-Q1 device uses
synchronous rectification. During the decay cycle, the body diode is shorted by the low-r_DS(on) driver, which in turn
reduces power dissipation in the full-bridge. In order to prevent shoot through (high-side and low-side drivers on
the same side are ON at the same time), the DRV8801A-Q1 device implements a 500-ns typical crossover delay
time. During this period, the body diode in the decay current path conducts the current until the DMOS driver
turns on. High-current and high-ambient-temperature applications should take this into consideration. In addition,
motor parameters and switching losses can add power dissipation that could affect critical applications.
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