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General Description

The MAX3967A is a programmable LED driver for fiber

optic transmitters operating at data rates up to

270Mbps. The circuit contains a high-speed current dri-

ver with programmable temperature coefficient (temp-

co), adjustments for LED prebias voltage, and a disable

feature. The circuit accepts PECL data inputs, and

operates from a single +2.97V to +5.5V power supply.

The SFP LED driver can switch up to 100mA into typical

high-speed light-emitting diodes. As temperature

increases, the device’s modulation current increases

with a tempco that is programmable from 2500ppm/°C

to 12,000ppm/°C. The modulation current is pro-

grammed with a single external resistor.

The MAX3967A’s LED prebias voltage is programmable

from 400mV to 925mV. The prebias circuit produces

peaking current, which improves the LED switching

speed.

Complementary current outputs help to maintain a con-

stant supply current, reducing EMI and supply noise

generated by the transmitter module. The MAX3967A is

available in die form, or in a 4mm x 4mm, 24-pin thin

QFN package.

Applications

Multimode LED Transmitters

Fast Ethernet/FDDI

155Mbps LAN ATM Transceivers

ESCON Receivers

SFP Transceivers

Features

♦ TX_DISABLE for SFP Compatibility

♦ Single +2.97V to +5.5V Power Supply

♦ Adjustable Temperature Compensation

♦ Adjustable Modulation Current

♦ Complementary Output Reduces Supply Noise

♦ Programmable LED Prebias Voltage

♦ Available in 24-Pin Thin QFN or Die

MAX3967A

270Mbps SFP LED Driver

________________________________________________________________ Maxim Integrated Products 1

TOP VIEW

THE EXPOSED PAD MUST BE CONNECTED TO GROUND FOR

PROPER THERMAL AND ELECTRICAL PERFORMANCE

MAX3967A

THIN QFN (4mm x 4mm)

TCNOM

123 456

131415161718

PB1

PB2

PB3

EEOUT

OUT+

OUT-

N.C.

CCOUT

N.C.

MON

MODSET

IN-

IN+

TX_DISABLE

TCMIN

EEOUT

OUT-

Pin Configuration

19-3629; Rev 0; 3/05

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.

Ordering Information

PART TEMP RANGE PIN-PACKAGE

MAX3967AETG -40°C to +85°C 24 Thin QFN

MAX3967AE/D -40°C to +85°C Dice*

Typical Operating Circuits appear at end of data sheet.

*Dice are tested and guaranteed only at T

= +25°C.

Summary of content (14 pages)

PAGE 1
9-3629; Rev 0; 3/05 270Mbps SFP LED Driver Features The MAX3967A is a programmable LED driver for fiber optic transmitters operating at data rates up to 270Mbps. The circuit contains a high-speed current driver with programmable temperature coefficient (tempco), adjustments for LED prebias voltage, and a disable feature. The circuit accepts PECL data inputs, and operates from a single +2.97V to +5.5V power supply.
PAGE 2
MAX3967A 270Mbps SFP LED Driver ABSOLUTE MAXIMUM RATINGS Supply Voltage at VCC, VCCOUT (VEE, VEEOUT = 0V) ..............................................-0.5V to +7V Current into OUT+, OUT- ................................-40mA to +160mA Differential Output Voltage (OUT+ to OUT-) .........-3.3V to +3.3V Voltage at PB1, PB2, PB3, IN+, IN-, OUT+, OUT-, TX_DISABLE......-0.5V to (VCC + 0.5V) Voltage at TCMIN, TCNOM, TC, MODSET, MON ....-0.
PAGE 3
270Mbps SFP LED Driver (Load as specified in Figure 1, unless otherwise noted. VCC = +2.97V to +5.5V (at the VCC pins), RMODSET = 1kΩ, TA = -40°C to +85°C. Input data shaped by 470MHz 4-pole filter, PB1 = PB2 = VEE, PB3 = open. Typical values are at VCC = +3.3V, TC connected to TCMIN, TA = +25°C.) (Note 4) PARAMETER SYMBOL CONDITIONS MIN Data Input Range Differential input 500 Output-Current Edge Speed 20% to 80%, input is a 12.
PAGE 4
Typical Operating Characteristics (MAX3967AETG in Maxim evaluation board, VCC = +3.3V, PB1 = PB2 = VEE, PB3 = open, TC connected to TCNOM, RMODSET = 1kΩ, TA = +25°C, unless otherwise noted.) MODULATION CURRENT vs. TEMPERATURE VCC = 5.0V 34 32 30 28 VCC = 3.
PAGE 5
270Mbps SFP LED Driver EYE DIAGRAM (OPTICAL) 155Mbps RANDOM JITTER vs. TEMPERATURE MAX3967 toc11 MAX3967 toc10 6 MAX3967 toc12 EYE DIAGRAM (OPTICAL) 155Mbps RANDOM JITTER (psRMS) 5 VCC = 3.3V MAXIMUM TEMPCO 4 3 2 1 VCC = 5.0V MINIMUM TEMPCO 0 1ns/div RECEIVER BW = 200MHz, VCC = 2.97V, TA = -40°C, PAVE = -15.8dBm, PATTERN = 231 - 1 PRBS 1ns/div RECEIVER BW = 200MHz, VCC = 5.5V, TA = +85°C, PAVE = -17.
PAGE 6
270Mbps SFP LED Driver MAX3967A Pin Description PIN NAME FUNCTION 1 TCNOM 2 TC 3, 4, 5 PB1, PB2, PB3 6, 7 VEEOUT 8, 9 OUT+ Current Output 10, 11 OUT- Complementary Current Output 12, 16 N.C. No Connection. Not internally connected.
PAGE 7
270Mbps SFP LED Driver MAX3967A TX_DISABLE VCCOUT OUTMAX3967A INPUT BUFFER IN+ 5Ω 0 1 COMPLEMENTARY OUTPUT 24X 0 IN- MODULATIONCURRENT GENERATOR RPREBIAS 78Ω MAIN OUTPUT 24X OUT+ GAIN 4X VCC 35Ω REFERENCE-VOLTAGE GENERATOR 12pF 1.2V V TEMP TCMIN TCNOM TC PREBIAS-CURRENT GENERATOR 50Ω MODSET RMODSET MON PB1 PB2 PB3 Figure 2.
PAGE 8
MAX3967A 270Mbps SFP LED Driver Table 1. LED Prebias Voltage PB1 PB2 PB3 PREBIAS (V) See the Modulation Current Tempco vs. RTC graph in the Typical Operating Characteristics to program a custom tempco. From the graph, determine the appropriate resistor and connect it between TCMIN and TC. For example, if an LED requires a 5000ppm/°C tempco, choose RTC of 8.3kΩ. Open Open Open 0.400 VEE Open Open 0.475 Open VEE Open 0.550 VEE VEE Open 0.
PAGE 9
270Mbps SFP LED Driver Exposed-Pad Package The exposed pad on the 24-pin TQFN provides a very low thermal resistance path for heat removal from the IC. MAX3967A PECL OUTPUT IN+ Chip Information TRANSISTOR COUNT: 331 SUBSTRATE CONNECTED TO VEE PROCESS: BIPOLAR DIE THICKNESS: 15 mils 50Ω VCC - 2V VCC R1 MAX3967A RF OR NON-PECL OUTPUT IN+ R2 VCC R1 R2 3.3 82 130 5.0 68 180 SINGLE-ENDED TERMINATION IS SHOWN. IN- SHOULD BE TERMINATED SIMILARLY. Figure 3.
PAGE 10
270Mbps SFP LED Driver MAX3967A Typical Operating Circuits SFP TRANSMITTER +3.3V FERRITE BEAD 10kΩ VCC DISABLE +3.3V 82Ω VCCOUT TX_DISABLE OUT- +3.3V OUT+ 82Ω MAX3967A CIN IN+ DIFFERENTIAL DATA VEEOUT IN- CIN VEE PB1 120Ω PB3 TCNOM TCMIN PB2 MODSET TC 120Ω RMODSET SFP TRANSMITTER WITH DIGITAL MONITOR +3.3V FERRITE BEAD 10kΩ VCC DISABLE +3.3V 82Ω VCCOUT TX_DISABLE OUT- +3.
PAGE 11
270Mbps SFP LED Driver SFF TRANSMITTER WITH DISABLE VCC VCC DISABLE PECL DATA FERRITE BEAD VCCOUT TX_DISABLE OUT- IN+ OUT+ MAX3967A IN- VEEOUT MON VEE PB1 PB2 TC PB3 TCNOM TCMIN MODSET RMODSET RTC* *OPTIONAL COMPONENT SFF TRANSMITTER WITHOUT DISABLE VCC VCC FERRITE BEAD VCCOUT TX_DISABLE PECL DATA OUT- OUT+ IN+ MAX3967A IN- VEEOUT MON PB1 VEE PB2 PB3 TCNOM TCMIN TC MODSET RMODSET ______________________________________________________________________________________ 11 M
PAGE 12
MAX3967A 270Mbps SFP LED Driver Chip Topography TX_DISABLE VEE IN+ PAD NAME BP1 TCMIN BP2 TCNOM 0 1268 BP3 TC 0 1060 BP4 PB1 0 876 BP5 PB2 0 744 BP6 PB3 0 560 BP7 VEEOUT 0 116 BP8 VEEOUT 0 0 BP9 OUT+ 180 0 BP10 OUT+ 296 0 BP11 OUT- 480 0 BP12 OUT- 596 0 BP13 VCCOUT 804 0 BP14 VCCOUT 804 124 BP15 VCC 804 528 BP16 MON 804 1032 VCCOUT BP17 MODSET 804 1240 VCCOUT BP18 VCC 804 1464 BP19 IN- 624 1464 VCC TCNOM MODSET TC MON PB1 1
PAGE 13
270Mbps SFP LED Driver 24L QFN THIN.EPS PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm 21-0139 PART PACKAGE TYPE MAX3967AETG 24 thin QFN (4mm x 4mm x 0.8mm) D 1 2 PACKAGE CODE T2444-4 ______________________________________________________________________________________ 13 MAX3967A 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 14
MAX3967A 270Mbps SFP LED Driver Package Information(continued) (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.) PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm 21-0139 D 2 2 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.