PM6644 datasheet(29/35 Pages) STMICROELECTRONICS

29 / 35 page

PM6644

Conclusion

Doc ID 023203 Rev 1

29/35

Conclusion

The device regulates VOUT = 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

PM6644 Datasheet(PDF) 29 Page - STMicroelectronics