19-3629; Rev 0; 3/05
270Mbps SFP LED Driver
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.
♦
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
Features
MAX3967A
Ordering Information
PART
MAX3967AETG
MAX3967AE/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 T
A
= +25°C.
Applications
Multimode LED Transmitters
MODSET
Pin Configuration
V
CCOUT
14
V
CCOUT
13
12
11
10
N.C.
OUT-
OUT-
OUT+
OUT+
V
EEOUT
9
8
7
1
TCNOM
2
TC
3
PB1
4
PB2
5
PB3
6
V
EEOUT
TOP VIEW
Fast Ethernet/FDDI
155Mbps LAN ATM Transceivers
ESCON Receivers
SFP Transceivers
MON
N.C.
16
18
V
CC
IN-
IN+
TX_DISABLE
19
20
21
22
23
24
17
15
MAX3967A
Typical Operating Circuits appear at end of data sheet.
V
EE
TCMIN
THIN QFN (4mm x 4mm)
THE EXPOSED PAD MUST BE CONNECTED TO GROUND FOR
PROPER THERMAL AND ELECTRICAL PERFORMANCE
________________________________________________________________
Maxim Integrated Products
V
CC
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.
270Mbps SFP LED Driver
MAX3967A
ABSOLUTE MAXIMUM RATINGS
Supply Voltage at V
CC
, V
CCOUT
(V
EE
, V
EEOUT
= 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 (V
CC
+ 0.5V)
Voltage at TCMIN, TCNOM, TC, MODSET, MON ....-0.5V to +2V
Continuous Power Dissipation (T
A
= +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...................................................+375°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; V
CC
= +2.97V to +5.5V (at the V
CC
pins); V
EE
, V
EEOUT
= 0V; T
A
= -40°C to +85°C, unless otherwise
noted. Temperature coefficients are referenced to T
A
= +25°C. Typical values are at V
CC
= +3.3V, T
A
= +25°C, unless otherwise
noted. Dice are tested at T
A
= +25°C only.)
PARAMETER
Data Input High Voltage
Data Input Low Voltage
Supply Current
Input Current at IN+ or IN-
R
MODSET
= 698Ω
(Note 2)
T
A
= -40°C
T
A
= +25°C
T
A
= +85°C
Modulation Current
R
MODSET
= 3.0kΩ
(Note 2)
T
A
= -40°C
T
A
= +25°C
T
A
= +85°C
R
MODSET
= 1.0kΩ
(Note 2)
T
A
= -40°C
T
A
= +25°C V
CC
= 3.3V
17.5
21.9
65
79
90
0.368
0.575
0.848
112
126
I
CC
SYMBOL
CONDITIONS
Referenced to V
CC
, DC-coupled input
Referenced to V
CC
, DC-coupled input
(Note 1)
-50
109
126
140
15.3
19.8
24
74
86
96
0.400
0.625
0.925
12,000
3600
2500
66
Resistance to V
EE
(Note 3)
V
IH
V
IL
I
MON
/ I
MODSET
, V
MON
< 1.1V,
R
MODSET
= 1kΩ, TC = TCMIN
0.92
1
50
2.0
0.8
1.08
78
65
90
100
Ω
kΩ
V
V
A/A
ppm/°C
25
28.7
89
89
110
0.451
0.696
1.026
V
mA
140
155
MIN
-1.165
-1.810
30
TYP
MAX
-0.880
-1.475
39
+50
UNITS
V
V
mA
µA
T
A
= +85°C
PB1, PB2, PB3 = (open, open, open)
Prebias Voltage
PB1, PB2, PB3 = (V
EE
, V
EE
, open)
PB1, PB2, PB3 = (V
EE
, V
EE
, V
EE
)
Maximum tempco (TC open)
Temperature Coefficient of
Modulation Current
Prebias Resistor
TX_DISABLE Resistance
TX_DISABLE High
TX_DISABLE Low
Monitor Gain
R
PREBIAS
Nominal tempco (TC shorted to TCNOM)
Minimum tempco (TC shorted to TCMIN)
Note 1:
R
MODSET
= 1kΩ. Excludes I
OUT
+ and I
OUT
-, TX_DISABLE high or low.
Note 2:
TC connected to TCMIN, PB1 = PB2 = V
EE
, PB3 = open.
Note 3:
The TX_DISABLE pin is internally pulled low. The driver is enabled when TX_DISABLE is left open.
2
_______________________________________________________________________________________
270Mbps SFP LED Driver
AC ELECTRICAL CHARACTERISTICS
(Load as specified in Figure 1, unless otherwise noted. V
CC
= +2.97V to +5.5V (at the V
CC
pins), R
MODSET
= 1kΩ, T
A
= -40°C to
+85°C. Input data shaped by 470MHz 4-pole filter, PB1 = PB2 = V
EE
, PB3 = open. Typical values are at V
CC
= +3.3V, TC connected
to TCMIN, T
A
= +25°C.) (Note 4)
PARAMETER
Data Input Range
Output-Current Edge Speed
Output-Current Pulse-Width
Correction (PWC)
Output-Current Data-Dependent
Jitter
Random Jitter
TX_DISABLE Assert Time
TX_DISABLE Negate Time
Power-On Time
DJ
RJ
t_off
t_on
t_init
Time from rising edge of TX_DISABLE to
output at 10% of steady state
Time from rising edge of TX_DISABLE to
output at 90% of steady state
Time from V
CC
> 2.97V to output at 90% of
steady state
SYMBOL
CONDITIONS
Differential input
20% to 80%, input is a 12.5MHz square wave
(Note 5)
266Mbps (Note 6)
155Mbps (Note 7)
MIN
500
300
615
-90
140
150
3
0.01
0.01
0.1
0.5
0.5
2
250
TYP
MAX
2400
1230
UNITS
mV
P-P
ps
ps
ps
P-P
ps
RMS
µs
µs
ms
MAX3967A
Note 4:
Note 5:
Note 6:
Note 7:
AC characteristics are guaranteed by design and characterization.
PWC = (width
CURRENT ON
- width
CURRENT OFF
) / 2.
Test pattern is a K28.5 (0011 1110 1011 0000 0101) transmitted at 266Mbps.
Test pattern is equivalent to a 2
13
- 1 PRBS containing 72 consecutive zeros or 72 consecutive ones.
V
CC
V
CC
V
LED
1.55V
V
CC
V
PREBIAS
OUT-
OUT+
OUT-
L1
FERRITE
BEAD
OSCILLOSCOPE
0.22µF
OUT-
OUT+
50Ω
5Ω
MAX3967A
MAX3967A
MAX3967A
0.22µF
50Ω
SWITCHING DIODE
OUT+
DC ELECTRICAL LOAD
(EXCEPT PREBIAS VOLTAGE)
DC ELECTRICAL LOAD
FOR PREBIAS VOLTAGE
AC ELECTRICAL LOAD
Figure 1. MAX3967A Output Test Loads
_______________________________________________________________________________________
3
270Mbps SFP LED Driver
MAX3967A
Typical Operating Characteristics
(MAX3967AETG in Maxim evaluation board, V
CC
= +3.3V, PB1 = PB2 = V
EE
, PB3 = open, TC connected to TCNOM, R
MODSET
=
1kΩ, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE
MAX3967 toc01
MODULATION CURRENT
vs. TEMPERATURE
MAX3967 toc02
DIE MODULATION CURRENT
vs. TEMPERATURE
MAX3967 toc03
40
38
36
SUPPLY CURRENT (mA)
34
32
30
28
26
24
22
20
V
CC
= 3.3V
V
CC
= 5.0V
EXCLUDES CURRENT INTO OUT+ AND OUT-
120
NOMINAL TEMPCO
MODULATION CURRENT (mA)
100
80
60
40
MAXIMUM TEMPCO
20
0
MINIMUM TEMPCO
120
100
80
60
MAXIMUM TEMPCO
40
20
0
NOMINALTEMPCO
MINIMUM TEMPCO
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
AMBIENT TEMPERATURE (
°
C)
-40
-20
0
20
40
60
80
MODULATION CURRENT (mA)
0
20
40
60
80
100
120
140
AMBIENT TEMPERATURE (
°
C)
JUNCTION TEMPERATURE (
°
C)
MODULATION CURRENT TEMPCO
vs. R
TC
MAX3967 toc04
MODULATION CURRENT
vs. R
MODSET
MAX3967 toc05
DIE MODULATION CURRENT
vs. R
MODSET
MAX3967 toc06
100,000
MODULATION CURRENT TEMPCO (ppm/
°
C)
200
NOMINAL TEMPCO
MODULATION CURRENT (mA)
100
MINIMUM TEMPCO
200
MODULATION CURRENT (mA)
100
MINIMUM TEMPCO
10,000
MAXIMUM TEMPCO
NOMINAL TEMPCO
MAXIMUM TEMPCO
1000
1
10
R
TC
(kΩ)
100
10
500
1k
R
MODSET
(Ω)
10k
10
500
1k
R
MODSET
(Ω)
8k
EYE DIAGRAM (ELECTRICAL)
266Mbps
MAX3967 toc07
EYE DIAGRAM (OPTICAL)
155Mbps
MAX3967 toc08
EYE DIAGRAM (OPTICAL)
155Mbps
MAX3967 toc09
500ps/div
PATTERN = 2
31
- 1 PRBS
1ns/div
RECEIVER BW = 200MHz, V
CC
= 2.97V, T
A
= +85
°
C,
P
AVE
= -17.1dBm, PATTERN = 2
31
- 1 PRBS
1ns/div
RECEIVER BW = 200MHz, V
CC
= 5.5V, T
A
= -40
°
C,
P
AVE
= -15.8dBm, PATTERN = 2
31
- 1 PRBS
4
_______________________________________________________________________________________
270Mbps SFP LED Driver
Typical Operating Characteristics (continued)
(MAX3967AETG in Maxim evaluation board, V
CC
= +3.3V, PB1 = PB2 = V
EE
, PB3 = open, TC connected to TCNOM, R
MODSET
=
1kΩ, T
A
= +25°C, unless otherwise noted.)
EYE DIAGRAM (OPTICAL)
155Mbps
MAX3967 toc10
MAX3967A
EYE DIAGRAM (OPTICAL)
155Mbps
MAX3967 toc11
RANDOM JITTER
vs. TEMPERATURE
MAX3967 toc12
6
5
RANDOM JITTER (ps
RMS
)
4
3
2
1
0
V
CC
= 3.3V
MAXIMUM TEMPCO
V
CC
= 5.0V
MINIMUM TEMPCO
0
10
20
30
40
50
60
70
80 90
AMBIENT TEMPERATURE (
°
C)
1ns/div
RECEIVER BW = 200MHz, V
CC
= 5.5V, T
A
= +85
°
C,
P
AVE
= -17.1dBm, PATTERN = 2
31
- 1 PRBS
1ns/div
RECEIVER BW = 200MHz, V
CC
= 2.97V, T
A
= -40
°
C,
P
AVE
= -15.8dBm, PATTERN = 2
31
- 1 PRBS
TX_DISABLE NEGATE TIME
MAX3967 toc13
TX_DISABLE ASSERT TIME
MAX3967 toc14
LED
OUTPUT
LED
OUTPUT
t_on
TX_DISABLE
TX_DISABLE
t_off
4ns/div
4ns/div
_______________________________________________________________________________________
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