Minimize length and impedance of
GHx, SHx, GLx, and SLx traces. Use as few vias as possible to minimize parasitic
inductance. TI recommends to increase these trace widths shortly after routing
away from the device pin to minimize parasitic resistance.
Keep BSTx capacitors close to the
respective pins
Keep CPH/CPL flying capacitor as close to the device pins as possible
Keep PVDD capacitors close to PVDD pin
Keep VDRAIN capacitor close to VDRAIN pin to supply steady switching current for
the charge pump.
Additional bulk capacitance is
required to bypass the high current path on the external MOSFETs. This bulk
capacitance is placed to minimize the length of any high current paths through
the external MOSFETs. The connecting metal traces are as wide as possible, with
numerous vias connecting PCB layers. These practices minimize inductance and let
the bulk capacitor deliver high current.
Connect SLx pins to MOSFET source, not directly to GND, for accurate VDS
detection.
Route SNx/SPx pins in parallel
from the sense resistor to the device. Place filtering components close to the
device pins to minimize post-filter noise coupling. Maintain that SNx/SPx stays
separated from GND plane to achieve best CSA accuracy. The bypass capacitor
across VREF and GND is placed closer to the device pin.
The exposed pad is used for
thermal dissipation, not electrical grounding, and has a high-impedance
connection to the GND/AGND pins. Therefore, TI recommends to connect the exposed
pad to the best thermal GND, and to connect the GND/AGND pins to the
MCU-reference GND.