Micrel

TXRX_982_R1 Evaluation Board

September 2004

M9999-092304

2

Evaluation Board Setting

Driver Laser Coupling

Table 1 summarizes the setting of the board for the

two configurations, driver DC-coupled or AC-coupled

to the laser.

Configuration

Remove

Install

Driver and Laser

DC-Coupled

L2, L3, L7, L8,

R14, R6, R13,

C24, C36

Install a 0

at

C24 and C38.

Driver and Laser

AC-Coupled

L2, L3, L7, L8,

R14, R6, R13,

C24, C36

Table 1. Configuration Settings

Receiver Sensitivity and Hysteresis Setting

SY88973 Limiting Amplifier

The SY88973 limiting amplifier is the default post

amplifier installed on the board. It has a receive signal

LOS indicator. To improve the hysteresis on the

receive signal LOS, install R2 and uninstall R3. The

combination of R2 and R1 will determine the

sensitivity of the transceiver and hysteresis on the

receive signal LOS. Refer to the application note

entitled "Notes on Sensitivity and hysteresis in

Micrel's Post Amplifiers" available at

http://www.micrel.com/product-info/app_hints+notes.shtml.

SY88843 Limiting Amplifier

The SY88843 limiting amplifier has a signal detect

(SD) indicator. To improve the hysteresis on the

receive signal LOS, remove R2 and install R3, Q6,

and R23. The combination of R3 and R1 will

determine the sensitivity of the transceiver and

hysteresis on the SD. Refer to the application note

entitled "Notes on Sensitivity and hysteresis in

Micrel's Post Amplifiers" available at

TOSA and ROSA Installation

Check the pinout of the laser and receiver and install

them accordingly to the diagrams shown on Figure 1.

Top Pad

LD Anode

Top Pad

LD Cathode

Bottom Pad

PD Cathode

Bottom Pad

NC

Top Pad

DATA-

Top Pad

DATA+

Top Pad GND

Bottom Pad

RSSI

Bottom Pad

VCC

Figure 1. Mounting of Laser and Receive