V23818-C18-Lxx/L4xx

Description

Data Sheet

6

2003-06-06

Functional Description of SFF 2x5 Pin Row Transceiver

This transceiver is designed to transmit serial data via single mode fiber.

Figure 2

Functional Diagram

The receiver component converts the optical serial data into LVPECL compatible

electrical data (RD+ and RD–). The Signal Detect (SD, active high) shows whether an

optical signal is present.

The transmitter converts LVPECL compatible electrical serial data (TD+ and TD–) into

optical serial data.

The transmitter contains a laser driver circuit that drives the modulation and bias current

of the laser diode. The currents are controlled by a power control circuit to guarantee

constant output power of the laser over temperature and aging.

The power control uses the output of the monitor PIN diode (mechanically built into the

laser coupling unit) as a controlling signal, to prevent the laser power from exceeding the

operating limits.

Single fault condition is ensured by means of an integrated automatic shutdown circuit

that disables the laser when it detects laser fault to guarantee the laser eye safety.

The transceiver contains a supervisory circuit to control the power supply. This circuit

makes an internal reset signal whenever the supply voltage (

V

threshold (

V

voltage has risen above the reset threshold. During this time the laser is inactive.

A high signal on TDis enables the transmitter. If TDis is low or not connected the

transmitter is not affected.

Laser

Driver

Laser

Monitor

Power

Control

SD

TD+

RD+

RD

−

TD

−

Tx

Coupling Unit

Rx

Coupling Unit

e/o

o/e

o/e

TDis

File: 1351

Single

Mode

Fiber

Automatic

Shut-Down

Limiting

Amp

TIA