MAX3646(2004) Ver la hoja de datos (PDF) - Maxim Integrated

Número de pieza

componentes Descripción

Fabricante

MAX3646
(Rev.:2004)

155Mbps to 622Mbps SFF/SFP Laser Driver with Extinction Ratio Control

Maxim Integrated 

155Mbps to 622Mbps SFF/SFP

Laser Driver with Extinction Ratio Control

VCC

SHUTDOWN

IN+

IN-

SHUTDOWN

TX_FAULT

TX_DISABLE

RPULL = 45kΩ

IMD

1

PC_MON

RPC_MON

IBIAS

82

BC_MON

RBC_MON

INPUT BUFFER

MAX3646

DATA

PATH

IMOD

ENABLE

SAFETY LOGIC

AND

IBIAS

POWER DETECTOR ENABLE

VCC

xTC

x268

T > TTH

T

IBIAS

xK

OUT-

OUT+

IMOD

BIAS

VCC

RD

IBIAS

VBG

x1/2

APCSET RAPCSET

IAPCSET

MD

x1

IMD

CMD

TH_TEMP

RTH_TEMP

MODTCOMP

RMODTCOMP

VBG

MODSET MODBCOMP

APCFILT1

APCFILT2

RMODSET

RMODBCOMP

CAPC

Figure 4. Functional Diagram

Average power is regulated using APC, which keeps

constant current from a photodiode coupled to the

laser. Peak-to-peak power is maintained by compen-

sating the modulation current for reduced slope effi-

ciency (h) of laser over time and temperature:

PAVG = IMD/ρMON

PP-P = η x IMOD

Modulation compensation from bias increases the mod-

ulation current by a user-selected proportion (K) need-

ed to maintain peak-to-peak laser power as bias

current increases with temperature. Refer to Maxim

Application Note HFAN-02.21 for details:

K = ∆IMOD / ∆IBIAS

This provides a first-order approximation of the current

increase needed to maintain peak-to-peak power.

Slope efficiency decreases more rapidly as tempera-

ture increases. The MAX3646 provides additional tem-

perature compensation as temperature increases past

a user-defined threshold (TTH).

8 _______________________________________________________________________________________

Share Link: