Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - laser controller Laser diode driver (LWL) TQFN 24 Surface-mount

General Description

The MAX3735/MAX3735A are +3.3V laser drivers for

SFP/SFF applications from 155Mbps up to 2.7Gbps.

The devices accept differential input data and provide

bias and modulation currents for driving a laser. DC-

coupling to the laser allows for multirate applications

and reduces the number of external components. The

MAX3735/MAX3735A are fully compliant with the SFP

MSA timing and the SFF-8472 transmit diagnostic

requirements.

An automatic power-control (APC) feedback loop is incor-

porated to maintain a constant average optical power

over temperature and lifetime. The wide modulation cur-

rent range of 10mA to 60mA (up to 85mA AC-coupled)

and bias current of 1mA to 100mA make this product

ideal for driving FP/DFB laser diodes in fiber-optic mod-

ules. The resistor range for the laser current settings is

optimized to interface with the DS1858 SFP controller IC.

The MAX3735/MAX3735A provide transmit-disable con-

trol, a single-point latched transmit-failure monitor out-

put, photocurrent monitoring, and bias-current

monitoring to indicate when the APC loop is unable to

maintain the average optical power. The MAX3735A

also features improved multirate operation.

The MAX3735/MAX3735A come in package and die

form, and operate over the extended temperature

range of -40°C to +85°C.

Applications

Gigabit Ethernet SFP/SFF Transceiver Modules

1G/2G Fibre Channel SFP/SFF Transceiver

Modules

Multirate OC3 to OC48-FEC SFP/SFF Transceiver

Modules

Features

♦ SFP Reference Design Available

♦ Fully Compliant with SFP and SFF-8472 MSAs

♦ Programmable Modulation Current from 10mA to

60mA (DC-Coupled)

♦ Programmable Modulation Current from 10mA to

85mA (AC-Coupled)

♦ Programmable Bias Current from 1mA to 100mA

♦ Edge Transition Times <51ps

♦ 27mA (typ) Power-Supply Current

♦ Multirate 155Mbps to 2.7Gbps Operation

♦ Automatic Average Power Control

♦ On-Chip Pullup Resistor for TX_DISABLE

♦ 24-Pin 4mm × 4mm QFN package

MAX3735/MAX3735A

2.7Gbps, Low-Power SFP Laser Drivers

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

IN+

0.1µF

GND

MODSET

APCSET

APCFILT2

APCFILT1

SHUTDOWN

TX_FAULT

TX_DISABLE

BC_MON

PC_MON

BIAS

OUT+

OUT-

OPTIONAL SHUTDOWN

CIRCUITRY

IN-

REPRESENTS A CONTROLLED-IMPEDANCE TRANSMISSION LINE

SERDES

MAX3735

MAX3735A

0.1µF

+3.3V

FERRITE BEAD

+3.3V

10Ω

BC_MON

PC_MON

15Ω

0.01µF

DS1858/DS1859

CONTROLLER

APC

M0N2

M0N3

MON1

+3.3V

Typical Application Circuit

19-2529; Rev 2; 7/04

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

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

*Dice are designed to operate from -40°C to +85°C, but are

tested and guaranteed only at T

= +25°C.

**EP = Exposed pad.

+Denotes lead-free package.

PART TEMP RANGE PIN-PACKAGE

MAX3735E/D -40°C to +85°C Dice*

MAX3735ETG -40°C to +85°C 24 Thin QFN-EP**

MAX3735EGG -40°C to +85°C 24 QFN-EP**

MAX3735AETG -40°C to +85°C 24 Thin QFN-EP**

MAX3735AETG+ -40°C to +85°C 24 Thin QFN-EP**

Pin Configuration appears at end of data sheet.

EVALUATION KIT

AVAILABLE

Summary of content (18 pages)

PAGE 1
9-2529; Rev 2; 7/04 KIT ATION EVALU E L B AVAILA 2.7Gbps, Low-Power SFP Laser Drivers Features ♦ SFP Reference Design Available ♦ Fully Compliant with SFP and SFF-8472 MSAs ♦ Programmable Modulation Current from 10mA to 60mA (DC-Coupled) ♦ Programmable Modulation Current from 10mA to 85mA (AC-Coupled) ♦ Programmable Bias Current from 1mA to 100mA ♦ Edge Transition Times <51ps ♦ 27mA (typ) Power-Supply Current ♦ Multirate 155Mbps to 2.
PAGE 2
MAX3735/MAX3735A 2.7Gbps, Low-Power SFP Laser Drivers ABSOLUTE MAXIMUM RATINGS Supply Voltage, VCC..............................................-0.5V to +6.0V Current into BIAS, OUT+, OUT- ......................-20mA to +150mA Current into MD.....................................................-5mA to +5mA Voltage at IN+, IN-, TX_DISABLE, TX_FAULT, SHUTDOWN ...........................................-0.5V to (VCC + 0.5V) Voltage at BIAS, PC_MON, BC_MON, MODSET, APCSET .................................-0.
PAGE 3
2.7Gbps, Low-Power SFP Laser Drivers (VCC = +2.97V to +3.63V, TA = -40°C to +85°C. Typical values at VCC = +3.3V, IBIAS = 20mA, IMOD = 30mA, TA = +25°C, unless otherwise noted.
PAGE 4
MAX3735/MAX3735A 2.7Gbps, Low-Power SFP Laser Drivers ELECTRICAL CHARACTERISTICS (continued) (VCC = +2.97V to +3.63V, TA = -40°C to +85°C. Typical values at VCC = +3.3V, IBIAS = 20mA, IMOD = 30mA, TA= +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SAFETY FEATURES Excessive Bias-Current Comparator Threshold Range TX_FAULT always occurs for VBC_MON ≥ 1.38V, TX_FAULT never occurs for VBC_MON ≤ 1.22V 1.22 1.30 1.
PAGE 5
2.7Gbps, Low-Power SFP Laser Drivers MAX3735/MAX3735A VCC VCC VOLTAGE VIN+ (100mV min, 1200mV max) VIN- 30Ω 30Ω MAX3735 MAX3735A OUT- (VIN+) - (VIN-) (200mVP-P min, 2400mVP-P max) 30Ω 0.5pF OUT+ CURRENT IOUT+ OSCILLOSCOPE IOUT+ OUT+ IMOD 75Ω 50Ω TIME Figure 1. Required Input Signal and Output Polarity Figure 2. Output Termination for Characterization HOST BOARD MODULE FILTER DEFINED BY SFP MSA L1 1µH SOURCE NOISE VOLTAGE SUPPLY C1 0.1µF C2 10µF OPTIONAL C3 0.
PAGE 6
Typical Operating Characteristics (VCC = +3.3V, CAPC = 0.01µF, IBIAS = 20mA, and IMOD = 30mA, TA = +25°C, unless otherwise noted.) OPTICAL EYE OPTICAL EYE MAX3735 toc02 MAX3735 toc01 ER = 8.2dB, 2.7Gbps, 2.3GHz FILTER 27 - 1 PRBS, 1310nm FP LASER ER = 8.2dB, 1.25Gbps, 900MHz FILTER K28.5 PATTERN, 1310nm FP LASER 54ps/div 115ps/div OPTICAL EYE ELECTRICAL EYE MAX3735 toc03 MAX3735 toc04 2.
PAGE 7
2.7Gbps, Low-Power SFP Laser Drivers MODULATION CURRENT vs. RMODSET 2.5 90 80 1.4 1.5 1.0 1.2 60 IMD (mA) IMOD (mA) 50 40 0.5 0 10 35 60 0.8 20 0.4 10 0.2 0 -15 0 85 10 1 100 1 0 10 100 TEMPERATURE (°C) RMODSET (kΩ) RAPCSET (kΩ) EDGE TRANSITION TIME vs. MODULATION CURRENT DETERMINISTIC JITTER vs. MODULATION CURRENT RANDOM JITTER vs. MODULATION CURRENT 70 50 40 DJ (psP-P) 60 FALL TIME 50 40 30 DJ (INCLUDING PWD) 20 RISE TIME 2.5 2.0 1.5 1.0 0.5 10 30 3.
PAGE 8
MAX3735/MAX3735A 2.7Gbps, Low-Power SFP Laser Drivers Typical Operating Characteristics (continued) (VCC = +3.3V, CAPC = 0.01µF, IBIAS = 20mA, and IMOD = 30mA, TA = +25°C, unless otherwise noted.) RESPONSE TO FAULT TRANSMITTER DISABLE MAX3735 toc17 MAX3735 toc16 VCC 3.3V VPC_MON EXTERNALLY FORCED FAULT t_fault = 0.
PAGE 9
2.7Gbps, Low-Power SFP Laser Drivers PIN NAME 1, 4, 8, 14, 18 VCC FUNCTION 2 IN+ Noninverted Data Input 3 IN- Inverted Data Input 5 PC_MON Photodiode Current Monitor Output. Current out of this pin develops a ground-referenced voltage across an external resistor that is proportional to the monitor diode current. 6 BC_MON Bias Current Monitor Output. Current out of this pin develops a ground-referenced voltage across an external resistor that is proportional to the bias current.
PAGE 10
MAX3735/MAX3735A 2.7Gbps, Low-Power SFP Laser Drivers VCC SHUTDOWN VCC MAX3735 MAX3735A INPUT BUFFER IN+ 15Ω OUT- DATA PATH 100Ω IN- OUT+ VCC IMOD VCC BIAS IMD IBIAS VCC 1 PC_MON IBIAS ENABLE IMOD ENABLE RD VBG APCSET x38 IAPCSET RPC_MON VCC RAPCSET X270 SAFETY LOGIC AND POWER DETECTOR IBIAS 76 VBG BC_MON MD IMD CMD VCC x1 (4.7kΩ TO 10kΩ) RBC_MON MODSET RMODSET APCFILT1 TX_FAULT TX_DISABLE APCFILT2 SHUTDOWN CAPC Figure 4.
PAGE 11
2.7Gbps, Low-Power SFP Laser Drivers POR AND COUNTER FOR t_init MAX3735/MAX3735A VCC MAX3735 MAX3735A IMOD ENABLE TX_DISABLE 100ns DELAY COUNTER FOR t_onfault IBIAS ENABLE VCC IMD R VBG PC_MON RS LATCH COMP RPC_MON Q 1 VCC SHUTDOWN S IBIAS BC_MON RBC_MON VBG CMOS 76 MODSET SHORTCIRCUIT DETECTOR TX_FAULT COMP TTL OPEN COLLECTOR Figure 5. Safety Circuitry Table 1. Typical Fault Conditions 1.
PAGE 12
MAX3735/MAX3735A 2.7Gbps, Low-Power SFP Laser Drivers Table 2. Circuit Responses to Various Single-Point Faults CIRCUIT RESPONSE TO OVERVOLTAGE OR SHORT TO V CC PIN NAME TX_FAULT CIRCUIT RESPONSE TO UNDERVOLTAGE OR SHORT TO GROUND Does not affect laser power. Does not affect laser power. Modulation and bias currents are disabled. Normal condition for circuit operation. IN+ The optical average power increases and a fault occurs if VPC_MON exceeds the threshold.
PAGE 13
2.7Gbps, Low-Power SFP Laser Drivers Determine RAPCSET The desired monitor diode current is estimated by IMD = PAVG x ρMON = 200µA. The Monitor Diode vs. RAPCSET graph in the Typical Operating Characteristics section shows that RAPCSET should be 3kΩ. The value can also be estimated using the equation below: IMD = 1.23 / (2 × RAPCSET) Optional Shutdown Output Circuitry The SHUTDOWN control output features extended eye safety when the laser cathode is grounded.
PAGE 14
MAX3735/MAX3735A 2.7Gbps, Low-Power SFP Laser Drivers Capacitors Used with MAX3735/MAX3735A SFP Module Designs for more information on choosing CAPC for DCand AC-coupled laser interfaces. MAX3735 Use the following equation to find the CAPC value when using the MAX3735: CAPC = 4.04 × 10-9 × t_on × η × ρMON (29.3 + 20.6 ITH 0.22 ITH2) × (1947 + 833 IMOD - 7.78 IMOD2 + 0.103 IMOD3) where units are: CAPC in µF, ITH, and IMOD in mA and tON in µs.
PAGE 15
2.7Gbps, Low-Power SFP Laser Drivers 0.079" (2.007mm) GND 7 VCC 6 IN+ 5 IN- 4 VCC 3 PC_MON 2 BC_MON 1 TX_DISABLE APCSET 8 9 GND 10 APCFILT2 APCFILT1 11 12 MD GND 13 14 15 VCC 16 OUT- 17 OUT0.060" (1.
PAGE 16
Bonding Coordinates Pin Configuration X Y TX_DISABLE APCSET GND APCFILT2 APCFILT1 MD Table 5.
PAGE 17
2.7Gbps, Low-Power SFP Laser Drivers 12,16,20, 24L QFN.EPS PACKAGE OUTLINE 12,16,20,24L QFN, 4x4x0.90 MM 21-0106 E 1 2 PACKAGE OUTLINE 12,16,20,24L QFN, 4x4x0.90 MM 21-0106 E 2 2 ______________________________________________________________________________________ 17 MAX3735/MAX3735A Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.
PAGE 18
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) 24L QFN THIN.EPS MAX3735/MAX3735A 2.7Gbps, Low-Power SFP Laser Drivers PACKAGE OUTLINE 12, 16, 20, 24L THIN QFN, 4x4x0.8mm 21-0139 C 1 2 PACKAGE OUTLINE 12, 16, 20, 24L THIN QFN, 4x4x0.