STCF07 datasheet(15/26 Pages) STMICROELECTRONICS

15 / 26 page

STCF07

PCB design

Doc ID 16757 Rev 3

15/26

PCB design

9.1

PCB design rules

The STCF07 is a powerful switched device, so the PCB must be designed following the

rules for designing switched supplies. It is recommended to use at least a two-layer PCB.

The power wiring must be as short and wide as possible, due to the high current. All external

components should be placed close to the STCF07. High-energy switched loops should be

as small as possible to reduce EMI. Most LEDs require cooling, which may be implemented

by a defined copper area on the PCB. Use the reference guide for each LED to design the

heatsink. Place the RFLASH resistor as close as possible to pins 5 and 6. When a change of

PCB layer is required, the number of vias must be sufficient. Place the NTC resistor as close

as possible to the LED for good temperature sensing. Direct connection of GND and PGND

is needed to achieve accurate output current values. The LED current should not flow

through this track. Sensing of the voltage on the RFLASH resistor must be done by

connecting a wire directly from pin 6 to the RFLASH resistor; no current flows through this

track. Pins 5 and 6 must be connected to the pin of the RFLASH resistor. The exposed pad

must be connected to the PGND, with a track as wide as possible. It is recommended to

place the copper plate, connected through the vias to the exposed pad, on the bottom layer

to create a heatsink for the device. It is further recommended that the copper plate used be

as large as possible to achieve optimal thermal performance.

STCF07 Datasheet(PDF) 15 Page - STMicroelectronics