Datasheet

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General Description

The MAX3669 is a complete, +3.3V laser driver with auto-

matic power control (APC) circuitry for SDH/SONET appli-

cations up to 622Mbps. It accepts differential PECL

inputs, provides bias and modulation currents, and oper-

ates over a temperature range from -40°C to +85°C.

An APC feedback loop is incorporated to maintain a

constant average optical power over temperature and

lifetime. The wide modulation current range from 5mA to

75mA and bias current of 1mA to 80mA are easy to

program, making this product ideal for use in various

SDH/SONET applications. Two pins are provided to

monitor the current levels in the laser: BIASMON with

current proportional to laser bias current, and MODMON

with current proportional to laser modulation.

The MAX3669 also provides enable control and a failure-

monitor output to indicate when the APC loop is unable

to maintain the average optical power. The MAX3669

is available in 4mm x 4mm 24-pin thin QFN and

5mm x 5mm 32-pin TQFP packages.

Applications

622Mbps SDH/SONET Access Nodes

Laser Driver Transmitters

Section Regenerators

Features

♦♦

+3.3V or +5.0V Single-Supply Operation

♦♦

40mA Supply Current at +3.3V

♦♦

Programmable Bias Current from 1mA to 80mA

♦♦

Programmable Modulation Current from

5mA to 75mA

♦♦

Bias Current and Modulation Current Monitors

♦♦

200ps Rise/Fall Time

♦♦

Automatic Average Power Control with Failure

Monitor

♦♦

Complies with ANSI, ITU, and Bellcore

SONET/SDH Specifications

♦♦

Enable Control

+3.3V, 622Mbps SDH/SONET

Laser Driver with Current Monitors and APC

MAX3669

For pricing, delivery, and ordering information, please contact Maxim Direct at

1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

EVALUATION KIT AVAILABLE

DATA+

BIASMAX

MODSET

APCSET

CAPC

FAIL

ENABLE

GND

BIAS

BIASMON

MODMON

OUT+

0.1μF

LASER

OUT-

100pF

FILT

20Ω

FILT

5pF

1μF

R+

20Ω

R-

6.3Ω

5Ω

FERRITE

BEAD

DATA-

PECL

+3.3V

84.5Ω

124Ω

4:1

SERIALIZER

WITH

CLOCK GEN

MAX3693

MAX3669

Typical Application Circuit

19-1575; Rev 6; 1/13

Ordering Information

Pin Configurations appear at end of data sheet.

PART TEMP RANGE PIN-PACKAGE

MAX3669ETG -40°C to +85°C 24 TQFN-EP*

MAX3669ETG+ -40°C to +85°C 24 TQFN-EP*

MAX3669EHJ -40°C to +85°C 32 TQFP

MAX3669EHJ+ -40°C to +85°C 32 TQFP

+Denotes a lead(Pb)-free/RoHS-compliant package.

*EP = Exposed pad.

Summary of content (13 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC General Description Features ♦ ♦ ♦ ♦ The MAX3669 is a complete, +3.3V laser driver with automatic power control (APC) circuitry for SDH/SONET applications up to 622Mbps. It accepts differential PECL inputs, provides bias and modulation currents, and operates over a temperature range from -40°C to +85°C.
PAGE 2
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC ABSOLUTE MAXIMUM RATINGS Supply Voltage, VCC .............................................-0.5V to +7.0V Current into BIAS ............................................-20mA to +150mA Current into OUT+, OUT- ............................... -20mA to +100mA Current into MD....................................................-5mA to +5mA Voltage at DATA+, DATA-, ENABLE, FAIL, BIASMON, MODMON ..................-0.5V to (VCC + 0.
PAGE 3
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC AC ELECTRICAL CHARACTERISTICS (VCC = +3.14V to +5.5V, load as shown in Figure 2, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25°C.
PAGE 4
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC Typical Operating Characteristics (VCC = +3.3V, TA = +25°C, unless otherwise noted.) ELECTRICAL EYE DIAGRAM (IMOD = 75mA) 223 – 1 PRBS MAX3669 TOC02 MAX3669 TOC01 ELECTRICAL EYE DIAGRAM (IMOD = 35mA) 622Mbps DATA RATE 622Mbps DATA RATE PATTERN = 213 - 1 + 80 CID IMOD = 75mA PATTERN = 213 - 1 + 80 CID IMOD = 35mA 200ps/div 200ps/div 200ps/div MONITOR DIODE CURRENT vs. APC SET RESISTOR BIAS CURRENT vs.
PAGE 5
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC Typical Operating Characteristics (continued) (VCC = +3.3V, TA = +25°C, unless otherwise noted.
PAGE 6
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC Pin Description PIN 6 NAME FUNCTION TQFN-EP TQFP 1, 13, 16, 19 1, 2, 6, 15, 17, 20, 24 VCC 2 3 DATA+ Positive PECL Data Input 3 4 DATA- Negative PECL Data Input 4, 8, 11, 17, 22 5, 10, 14, 21, 22, 30 GND Positive Supply Voltage Ground 5 7 BIASMON Sink Current Source. Proportional to the laser bias current. 6 8 MODMON Sink Current Source. Proportional to the laser modulation current.
PAGE 7
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC DATA+ IMOD OUT+ OUT- DATAVCC 100kΩ VCC ENABLE IBIAS RBIASMON 165X VCC BIAS MAX3669 40X 5X IBIAS 38 MD RMODMON IMD IMOD 29 FAILURE DETECTOR MODSET CAPC BIASMAX APCSET FAIL RMODSET RBIASMAX CAPC RAPCSET Figure 3.
PAGE 8
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC Automatic Power Control Enable Control To maintain constant average optical power, the MAX3669 incorporates an APC loop to compensate for the changes in laser threshold current over temperature and lifetime. A back-facet photodiode mounted in the laser package is used to convert the optical power into a photocurrent.
PAGE 9
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC Resistor graph in the Typical Operating Characteristics and select the value of R BIASMAX that corresponds to the required current at +25°C. When using the MAX3669 in closed-loop operation, the RBIASMAX resistor sets the maximum bias current available to the laser diode over temperature and life. The APC loop can subtract from this maximum value but cannot add to it. See the Bias Current vs.
PAGE 10
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC Calculate Power Consumption The total power dissipation of the MAX3669 can be estimated by the following: P = VCC x ICC + (VCC - Vf) x IBIAS + IMOD (VCC - 20Ω x IMOD / 2) where IBIAS is the maximum bias current set by RBIASMAX, IMOD is the modulation current, and Vf is the typi- In this example, IBIAS = 68.1mA. The Bias Current vs.
PAGE 11
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC At +5V power supply, the headroom voltage for the MAX3669 is significantly improved. In this case, it is possible to achieve a modulation current of more than 50mA (using resistor pullups as shown in the Typical Operating Circuit). The MAX3669 can also be DC-coupled to a laser diode when operating at +5V supply; the voltage at OUT+ should be ≥ 2.0V for proper operation.
PAGE 12
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC Chip Information SUBSTRATE CONNECTED TO GND Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 12 PACKAGE CODE OUTLINE NO.
PAGE 13
MAX3669 +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC Revision History REVISION NUMBER REVISION DATE 6 1/13 DESCRIPTION Removed dice option from data sheet; removed the Chip Topography section; added the Package Information table PAGES CHANGED 1, 2, 3, 11, 12 Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied.