Datasheet

PM6644 Conclusion
Doc ID 023203 Rev 1 29/35
5 Conclusion
The device regulates V
OUT
= 8 V properly with the designed schematic and bill of material.
The 12 V input voltage range should have an accuracy of ± 5%.
PCB design guidelines
The layout is very important in terms of efficiency, stability and system noise. It is possible to
refer to the PM6644 evaluation kit board for a complete layout example.
For good PC board layout, follow these guidelines:
● Place all the power components (inductors, input and output capacitors) on the top
side. Refer them to a ground plan, GND in an inner layer. Connect the exposed pad of
the PM6644 to the GND plan with vias (design a GND pad on the top side with the
same size as the exposed pad). On the top side connect the GND pin with a short trace
to the exposed pad.
● Place input capacitors close to the VIN pin, in order to minimize AC current drops
during high-side MOSFET turn-on. Add vias to the GND plan.
● Place the output capacitor close to the GND pin, in order to minimize AC current drops
during high-side and low-side MOSFET turn-on. Add vias to the GND plan.
● Place filtering capacitors close to pins REF3, BYP and VCC.
● Place the resistor near the TON pin in order to minimize parasitic capacitance on the
TON pin.
Figure 31. Recommended layout - top layer Figure 32. Recommended layout - inner layer