EVERLIGHT ELECTRONICS CO., LTD.

http://www.everlight.com

Rev 1.0

Page: 7 of 7

Device NO: DPL-155-001

Prepared Date:04-06-2004

Prepared By: Chin-Chia Hsu

PLR155 Series

Application Notes: PLR155 Series PCB layout for motherboard integration

To achieve better jitter and low input optical power performances, several PCB layout

guidelines must be followed. These guidelines ensure the most reliable PLR155 POF performance

for the motherboard integration. Failed to implement these PCB guidelines may affect the PLR155

jitter and low input power performances.

1. Careful decoupling of the power supplies is very important. Place a 0.1uf surface mount (size

805 or smaller) capacitor as close as (less than 2cm) to the POF Vdd and Gnd leads. The 0.1uf

act as a low impedance path to ground for any stray high frequency transient noises.

2. To reduce the digital noises form the digital IC on the motherboard, the planar capacitance

formed by an isolated Vcc and Gnd planes is critical. The POF device must be mounted directly

on these two planes to reduce the lead parasitic inductance.

3. The isolated Vdd and Gnd planes must be connected to the main Vcc and Gnd (digital) planes at

a single point using ferrite beads. The beads are used to block the high frequency noises from

the digital planes while still allowing the DC connections between the planes

EVERLIGHT ELECTRONICS CO., LTD.

Tel: 886-2-2267-2000, 2267-9936

Office: No 25, Lane 76, Sec 3, Chung Yang Rd,

Fax:886-2-2269-8114, 2267-6189, 2267-6306

Tucheng, Taipei 236, Taiwan, R.O.C

http://www.everlight.com