P9038 LAYOUT GUIDE
4
08/23/15
AN-894
Custom Layout Guidelines
The P9038 wireless power transmitter is an integrated device consisting of a high power full-bridge inverter designed to drive
wireless LC resonance circuits and transmit power to WPC complaint wireless receivers. In addition to wireless power transfer,
there are noise sensitive circuits, General Purpose I/O's (GPIO's) and two low power linear regulators. When designing the
printed circuit board (PCB) there are multiple considerations and often some trade-offs associated with managing the critical
current paths. In order to optimize the design, components should be placed based on circuit function to guarantee best
performance when the schematic is implemented into a PCB design. Furthermore, the thermal management of the application
is important to the product's performance and should be optimized during PCB design. By following the guidelines set forth in
this document, efficient operation will be obtained for each circuit function.
Layout Priority Checklist
1. Place the Input capacitors and use short, wide connections from IN to PGND (target < 250mils long, > 50 mils wide).
2. Route SW1 and SW2 wide and short (use 6 – 10 vias for layer transitions) (target < 250mils long, > 50 mils wide).
3. Use wide planes (up to 2A) to route from the power connector to the R
SENSE
& IN and PGND connections.
4. Use sense (Kelvin) connections to connect to the current sense resistor R
SENSE
. See
5. Create wide continuous connections to the EPAD on bottom or internal PCB layer(s) (at least two 200 to 400 mil wide
channels should be directly connected to the EPAD and uninterrupted by traces for at least 1" leading away from the
IC). Use 25 thermal vias in the EPAD.
6. Place LDO capacitors as close as possible to the P9038.
7. Place Vsns Diode near LC and use 10 mils+ air gap separation from the cathode to the first filter resistor.
8. Place HPF capacitor near the P9038 and shield from switching side with shield resistor.
Figure 2. P9038 Simplified Diagram
