11.3 Gbps Active Back-Termination,

Differential Laser Diode Driver

ADN2526

Rev. A

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FEATURES

3.3 V operation

Up to 11.3 Gbps operation

Typical 24 ps rise/fall times

Full back-termination of output transmission lines

Drives TOSAs with resistances ranging from 5 Ω to 50 Ω

Bias current range: 10 mA to 100 mA

Differential modulation current range: 10 mA to 80 mA

Voltage input control for bias and modulation currents

Data inputs sensitivity: 150 mV p-p diff

Automatic laser shutdown (ALS)

Cross point adjustment (CPA)

XFP-compliant bias current monitor

SFP+ MSA compliant

Optical evaluation board available

Compact 3 mm × 3 mm LFCSP

APPLICATIONS

SONET OC-192 and SDH STM-64 optical transceivers

10 Gb Fibre Channel transceivers

10 Gb Ethernet optical transceivers

SFP+/XFP/X2/XENPAK/XPAK/MSA 300 optical modules

GENERAL DESCRIPTION

The ADN2526 laser diode driver is designed for direct modula-

tion of packaged laser diodes that have a differential resistance

ranging from 5 Ω to 50 Ω. The active back-termination in the

ADN2526 absorbs signal reflections from the TOSA end of the

output transmission lines, enabling excellent optical eye quality to

be achieved even when the TOSA end of the output transmission

lines is significantly misterminated. ADN2526 is an SFP+ MSA-

compliant device, and its small package and enhanced ESD

protection provide the optimum solution for compact modules

where laser diodes are packaged in low pin-count optical

subassemblies.

The modulation and bias currents are programmable via the

MSET and BSET control pins. By driving these pins with control

voltages, the user has the flexibility to implement various

average optical power and extinction ratio control schemes,

including closed-loop or look-up table control. The automatic

laser shutdown (ALS) feature allows the user to turn on/off the

bias and modulation currents by driving the ALS pin with a

LVTTL logic source.

The product is available in a space-saving 3 mm × 3 mm LFCSP

specified from −40°C to +85°C.

FUNCTIONAL BLOCK DIAGRAM

50Ω

200Ω

800Ω

200Ω

2Ω

VCC

DATAP

DATAN

MSET

VEE

BSET

IBMON

IBIAS

IMODP

IMODN

ADN2526

VCC

ALS

VCC

CPA

GND

VCC

50Ω

50Ω

200Ω

800Ω

IMOD

CROSS

POINT

ADJUST

Figure 1.