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19-3252; Rev 0; 5/04
270Mbps SFP LED Driver
General Description
The MAX3967 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 MAX3967’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 MAX3967 is
available in die form, or in a 4mm x 4mm, 24-pin thin
QFN package.
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 QFN or Die
Ordering Information
PART
MAX3967ETG
MAX3967E/D
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
24 Thin QFN
Dice*
*Dice are tested and guaranteed only at TA = +25°C.
Applications
Multimode LED Transmitters
Fast Ethernet/FDDI
155Mbps LAN ATM Transceivers
ESCON Receivers
SFP Transceivers
Typical Operating Circuits appear at end of data sheet.
TOP VIEW
Pin Configuration
24 23 22 21 20 19
TCNOM 1
18 MODSET
TC 2
17 MON
PB1 3
PB2 4
MAX3967
16 N.C.
15 VCC
PB3 5
14 VCCOUT
VEEOUT 6
13 VCCOUT
7 8 9 10 11 12
THIN QFN (4mm x 4mm)
THE EXPOSED PAD MUST BE CONNECTED TO GROUND FOR
PROPER THERMAL AND ELECTRICAL PERFORMANCE
________________________________________________________________ Maxim Integrated Products 1
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.

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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 ....-0.5V to +2V
Continuous Power Dissipation (TA = +85°C)
24-Lead Thin QFN (derate 20.8mW/C°
above +85°C).............................................................1354mW
Operating Junction Temperature Range ...........-40°C to +150°C
Die Attach Temperature...................................................+400°C
Storage Temperature Range .............................-50°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(Load as specified in Figure 1; VCC = +2.97V to +5.5V (at the VCC pins); VEE, VEEOUT = 0V; TA = -40°C to +85°C, unless otherwise
noted. Temperature coefficients are referenced to TA = +25°C. Typical values are at VCC = +3.3V, TA = +25°C, unless otherwise
noted. Dice are tested at TA = +25°C only.)
PARAMETER
Data Input High Voltage
Data Input Low Voltage
Supply Current
Input Current at IN+ or IN-
Modulation Current
Prebias Voltage
Temperature Coefficient of
Modulation Current
Prebias Resistor
TX_DISABLE Resistance
TX_DISABLE High
TX_DISABLE Low
Monitor Gain
SYMBOL
CONDITIONS
Referenced to VCC, DC-coupled input
Referenced to VCC, DC-coupled input
ICC (Note1)
RMODSET = 698
(Note 2)
RMODSET = 3.0k
(Note 3)
(Note 3)
TA = -40°C
TA = +25°C
TA = +85°C
TA = -40°C
TA = +25°C
TA = +85°C
PB1, PB2, PB3 = (open, open, open)
PB1, PB2, PB3 = (VEE, VEE, open)
PB1, PB2, PB3 = (VEE, VEE, VEE)
Maximum tempco (TC open)
Nominal tempco (TC shorted to TCNOM)
Minimum tempco (TC shorted to TCMIN)
RPREBIAS
Resistance to VEE (Note 4)
VIH
VIL
IMON / IMODSET, VMON < 1.1V,
RMODSET = 1k, TC = TCMIN
MIN
-1.165
-1.810
-50
66.0
0.368
0.575
0.848
66
50
2.0
TYP
30
110
124
139
14
18
22
75
0.400
0.625
0.925
12,000
3600
2500
78
65
MAX
-0.880
-1.475
39
+50
84.5
0.451
0.696
1.026
90
100
0.8
UNITS
V
V
mA
µA
mA
V
ppm/°C
k
V
V
0.92 1 1.08 A/A
Note 1: RMODSET = 1k. Excludes IOUT+ and IOUT-, TX_DISABLE high or low.
Note 2: TC connected to TCMIN.
Note 3: VCC = +3.3V, VLED = 1.55V, prebias voltage programmed at 0.625V (nominal), TA = +25°C. RMODSET = 1k, (programs
approximately 80mA), TC connected to TCNOM.
Note 4: The TX_DISABLE pin is internally pulled low. The driver is enabled when TX_DISABLE is left open.
2 _______________________________________________________________________________________

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270Mbps SFP LED Driver
AC ELECTRICAL CHARACTERISTICS
(Load as specified in Figure 1, unless otherwise noted. VCC = +2.97V to +5.5V (at the VCC pins), RMODSET = 1k, TA = -40°C to
+85°C. Input data edge speed = 1ns (typ), PB1 = PB2 = VEE, PB3 = open. Typical values are at VCC = +3.3V, TC connected to
TCNOM, TA = +25°C.) (Note 5)
PARAMETER
Data Input Range
Output-Current Edge Speed
SYMBOL
CONDITIONS
Differential input
20% to 80%, input is a 12.5MHz square wave
MIN
500
300
TYP
615
Output-Current Pulse-Width
Correction (PWC)
Note 6
-80
Output-Current Data-Dependent
Jitter
Random Jitter
266Mbps (Note 7)
DJ
155Mbps (Note 8)
RJ
140
150
3
TX_DISABLE Assert Time
t_off Time from rising edge of TX_DISABLE to
output at 10% of steady state
0.01
TX_DISABLE Negate Time
t_on Time from rising edge of TX_DISABLE to
output at 90% of steady state
0.01
Power-On Time
t_init
Time from VCC > 2.97V to output at 90% of
steady state
0.1
Note 5: AC characteristics are guaranteed by design and characterization.
Note 6: PWC = (widthCURRENT ON - widthCURRENT OFF) / 2.
Note 7: Test pattern is a K28.5 (0011 1110 1011 0000 0101) transmitted at 266Mbps.
Note 8: Test pattern is equivanlent to a 213 - 1 PRBS containing 72 consecutive zeros or 72 consecutive ones.
MAX
2400
1230
UNITS
mVP-P
ps
ps
250 psP-P
psRMS
0.5 µs
0.5 µs
2 ms
VCC
OUT-
VLED
1.55V
VCC
VPREBIAS
OUT+
OUT- OUT+
MAX3967
MAX3967
VCC
L1
OUT-
FERRITE
BEAD
0.1µF
MAX3967
5
0.1µF
OSCILLOSCOPE
50
50
OUT+
SWITCHING DIODE
DC ELECTRICAL LOAD
(EXCEPT PREBIAS VOLTAGE)
DC ELECTRICAL LOAD
FOR PREBIAS VOLTAGE
Figure 1. MAX3967 Output Test Loads
AC ELECTRICAL LOAD
_______________________________________________________________________________________ 3

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270Mbps SFP LED Driver
Typical Operating Characteristics
(MAX3967ETG in Maxim evaluation board, VCC = +3.3V, PB1 = PB2 = VEE, PB3 = open, TC connected to TCNOM, RMODSET = 1k,
TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE
40
EXCLUDES CURRENT INTO OUT+ AND OUT-
38
36
34 VCC = 5.0V
32
30
28
26 VCC = 3.3V
24
22
20
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
AMBIENT TEMPERATURE (°C)
100,000
MODULATION CURRENT TEMPCO
vs. RTC
10,000
MODULATION CURRENT
vs. TEMPERATURE
120
NOMINAL TEMPCO
100 MINIMUM TEMPCO
80
60
40
MAXIMUM TEMPCO
20
0
-40
200
100
-20 0 20 40 60
AMBIENT TEMPERATURE (°C)
MODULATION CURRENT
vs. RMODSET
NOMINALTEMPCO
80
MINIMUM TEMPCO
DIE MODULATION CURRENT
vs. TEMPERATURE
120
100 MINIMUM TEMPCO
80
60
MAXIMUM TEMPCO
40
20 NOMINALTEMPCO
0
0
200
20 40 60 80 100 120 140
JUNCTION TEMPERATURE (°C)
DIE MODULATION CURRENT
vs. RMODSET
100 MINIMUM TEMPCO
1000
1
10
RTC (k)
100
EYE DIAGRAM (ELECTRICAL)
266Mbps
MAX3967 toc07
MAXIMUM TEMPCO
10
500
1k
RMODSET ()
10k
EYE DIAGRAM (OPTICAL)
155Mbps
MAX3967 toc08
NOMINALTEMPCO
10
500
MAXIMUM TEMPCO
1k
RMODSET ()
8k
EYE DIAGRAM (OPTICAL)
155Mbps
MAX3967 toc09
500ps/div
PATTERN = 231 - 1 PRBS
1ns/div
RECEIVER BW = 200MHz, VCC = 2.97V, TA = +85°C,
PAVE = -17.1dBm, PATTERN = 231 - 1 PRBS
1ns/div
RECEIVER BW = 200MHz, VCC = 5.5V, TA = -40°C,
PAVE = -15.8dBm, PATTERN = 231 - 1 PRBS
4 _______________________________________________________________________________________

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270Mbps SFP LED Driver
Typical Operating Characteristics (continued)
(MAX3967ETG in Maxim evaluation board, VCC = 3.3V, PB1 = PB2 = VEE, PB3 = open, TC connected to TCNOM, RMODSET = 1k,
TA = +25°C, unless otherwise noted.)
EYE DIAGRAM (OPTICAL)
155Mbps
MAX3967 toc10
EYE DIAGRAM (OPTICAL)
155Mbps
MAX3967 toc11
6
RANDOM JITTER
vs. TEMPERATURE
5
4
VCC = 3.3V
MAXIMUM TEMPCO
3
2
1ns/div
RECEIVER BW = 200MHz, VCC = 5.5V, TA = +85°C,
PAVE = -17.1dBm, PATTERN = 231 - 1 PRBS
1ns/div
RECEIVER BW = 200MHz, VCC = 2.97V, TA = -40°C,
PAVE = -15.8dBm, PATTERN = 231 - 1 PRBS
1
VCC = 5.0V
MINIMUM TEMPCO
0
0 10 20 30 40 50 60 70 80 90
AMBIENT TEMPERATURE (°C)
TX_DISABLE NEGATE TIME
MAX3967 toc13
TX_DISABLE ASSERT TIME
MAX3967 toc14
LED
OUTPUT
TX_DISABLE
t_on
4ns/div
LED
OUTPUT
TX_DISABLE
t_off
4ns/div
_______________________________________________________________________________________ 5