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Número de pieza | MAX3296CGISEVKIT | |
Descripción | MAX3296 Shortwave or VCSEL (Common Cathode) Evaluation Kit | |
Fabricantes | Maxim Integrated | |
Logotipo | ||
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No Preview Available ! 19-1550; Rev 6; 11/04
3.0V to 5.5V, 1.25Gbps/2.5Gbps
LAN Laser Drivers
General Description
The MAX3286/MAX3296 series of products are high-
speed laser drivers for fiber optic LAN transmitters opti-
mized for Gigabit Ethernet applications. Each device
contains a bias generator, laser modulator, and com-
prehensive safety features. Automatic power control
(APC) adjusts the laser bias current to maintain aver-
age optical power at a constant level, regardless of
changes in temperature or laser properties. For lasers
without a monitor photodiode, these products offer a
constant-current mode. The circuit can be configured
for use with conventional shortwave (780nm to 850nm)
or longwave (1300nm) laser diodes, as well as vertical-
cavity surface-emitting lasers (VCSELs).
The MAX3286 series (MAX3286–MAX3289) is opti-
mized for operation at 1.25Gbps, and the MAX3296
series (MAX3296–MAX3299) is optimized for 2.5Gbps
operation. Each device can switch 30mA of laser mod-
ulation current at the specified data rate. Adjustable
temperature compensation is provided to keep the opti-
cal extinction ratio within specifications over the operat-
ing temperature range. This series of devices is
optimized to drive lasers packaged in low-cost TO-46
headers. Deterministic jitter (DJ) for the MAX3286 is
typically 22ps, allowing a 72% margin to Gigabit
Ethernet DJ specifications.
These laser drivers provide extensive safety features to
guarantee single-point fault tolerance. Safety features
include dual enable inputs, dual shutdown circuits, and
a laser-power monitor. The safety circuit detects faults
that could cause dangerous light output levels. A pro-
grammable power-on reset pulse initializes the laser
driver at startup.
The MAX3286/MAX3296 are available in a compact, 5mm
✕ 5mm, 28-pin QFN or thin QFN package; a 5mm ✕ 5mm,
32-pin TQFP package; or in die form. The MAX3287/
MAX3288/MAX3289 and MAX3297/MAX3298/MAX3299
are available in a 16-pin TSSOP-EP package.
Applications
Gigabit Ethernet Optical Transmitter
Fibre Channel Optical Transmitter
ATM LAN Optical Transmitter
Features
♦ 7ps Deterministic Jitter (MAX3296)
22ps Deterministic Jitter (MAX3286)
♦ +3.0V to +5.5V Supply Voltage
♦ Selectable Laser Pinning (Common Cathode or
Common Anode) (MAX3286/MAX3296)
♦ 30mA Laser Modulation Current
♦ Temperature Compensation of Modulation Current
♦ Automatic Laser Power Control or Constant
Bias Current
♦ Integrated Safety Circuits
♦ Power-On Reset Signal
♦ QFN and Thin QFN Packages Available
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX3286CTI+
0°C to +70°C
28 Thin QFN
(5mm x 5mm)****
MAX3286CGI
0°C to +70°C
28 QFN
(5mm x 5mm)***
MAX3286CHJ
0°C to +70°C
32 TQFP
(5mm x 5mm)
Ordering Information continued at end of data sheet.
*Dice are designed to operate from TJ = 0°C to +110°C, but
are tested and guaranteed only at TA = +25°C.
**Exposed pad.
***Package Code: G2855-1
****Package Code: T2855-7
+Denotes Lead-Free Package.
Pin Configurations
TOP VIEW
FAULT
FAULT
POR
GND
EN
EN
PORDLY
1
2
3
4
5
6
7
+
MAX3286
MAX3296
21 BIASDRV
20 SHDNDRV
19 GND
18 MON
17 MD
16 POL
15 POL
Typical Application Circuits and Selector Guide appear at
end of data sheet.
THIN QFN*
*Exposed pad is connected to GND.
Pin Configurations continued at end of data sheet.
________________________________________________________________ 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.
1 page 3.0V to 5.5V, 1.25Gbps/2.5Gbps
LAN Laser Drivers
(TA = +25°C, unless otherwise noted.)
EN STARTUP
(COMMON-ANODE CONFIGURATION)
Typical Operating Characteristics (continued)
MD SHUTDOWN
EYE DIAGRAM
EN
FAULT
BIASDRV
OPTICAL
OUTPUT
5µs/div
MD
FAULT
SHDNDRV
OPTICAL
OUTPUT
10µs/div
100ps/div
1.25Gbps, 1310nm LASER, 27 - 1 PRBS, Imod = 15mA
QFN/
THIN QFN
MAX3286
MAX3296
1
—
2
3
4, 13, 19
PIN
TQFP
MAX3286
MAX3296
1
2, 16, 19
3
TSSOP-EP
MAX3287
MAX3297
MAX3289
MAX3299
—
—
—
4—
5, 14, 22, 30
1, 6
TSSOP-EP
MAX3288
MAX3298
—
—
—
—
1, 6
5 6 ——
6 7 ——
7 8 ——
Pin Description
NAME
FUNCTION
FAULT
N.C.
FAULT
POR
GND
EN
EN
PORDLY
Inverting Fault Indicator. See Table 1.
No Connect
Noninverting Fault Indicator. See Table 1.
Power-On Reset. POR is a TTL-compatible
output. See Figure 14.
Ground
Enable TTL Input. The laser output is enabled
only when EN is high and EN is low. If EN is
left unconnected, the laser is disabled.
Inverting Enable TTL Input. The laser output
is enabled only when EN is low or grounded
and EN is high. If EN is left unconnected, the
laser is disabled.
Power-On Reset Delay. To extend the delay
for the power-on reset circuit, connect a
capacitor to PORDLY. See the Design
Procedure section.
_______________________________________________________________________________________ 5
5 Page 3.0V to 5.5V, 1.25Gbps/2.5Gbps
LAN Laser Drivers
force a shutdown if a fault is detected. The shutdown
condition is latched until reset by a toggle of EN, EN, or
power.
Another safety system, open fiber control (OFC), uses
safety interlocks to prevent eye hazards. To accommo-
date the OFC standard, the MAX3286/MAX3296 series
provide dual enable inputs and dual fault outputs.
The safety circuitry contains fault detection, dual enable
inputs, latched fault outputs, and a pulse generator
(Figure 6).
Safety circuitry monitors the APC circuit to detect unsafe
levels of laser emission during single-point failures. A
single-point failure can be a short to VCC or GND or a
short between any two IC pins.
1.3
1.2
RTC ≥ 1.9kΩ
RMOD = OPEN
TEMPCO = 4000ppm/°C
1.1
1.0
0.9 RTC = OPEN
TEMPCO = 50ppm/°C
0.8
0.7
0.6
0 10 20 30 40 50 60 70 80 90 100 110
JUNCTION TEMPERATURE (°C)
Figure 5. Modulation Current vs. Temperature for Maximum
and Minimum Temperature Coefficient
Pulse Generator
During startup, the laser does not emit light and the
APC loop is not closed, triggering a fault signal. To
allow startup, an internal fault-delay pulse disables the
safety system for a programmable period of time, allowing
the driver to begin operation. The length of the pulse is
determined by the capacitor connected at FLTDLY and
should be set 5 to 10 times longer than the APC time
constant. The internal safety features can be disabled
by connecting FLTDLY to GND. Note that EN must be
high, EN must be low, and VCC must be in the opera-
tional range for laser operation.
Fault Detection
The MAX3286/MAX3296 series has extensive and com-
prehensive fault-detection features. All critical nodes
are monitored for safety faults, and any node voltage
that differs significantly from its expected value results
in a fault (Table 1). When a fault condition is detected,
the laser is shut down. See the Applications Information
section for more information on laser safety.
Shutdown
The laser drivers offer dual redundant bias shutdown
mechanisms. The SHDNDRV output drives an optional
external MOSFET semiconductor. The bias and modu-
lation drivers have separate internal disable signals.
Latched Fault Output
Two complementary FAULT outputs are provided with
the MAX3286/MAX3296 series. In the event of a fault,
these outputs latch until one of three events occurs:
1) The power is switched off, then on.
EN
VCC
EN
(FROM POR CIRCUIT)
FAULT
DETECTION
REF_FAULT
MONITOR_FAULT
MD_FAULT
POLARITY_FAULT
TC_FAULT
MOD_FAULT
PULSE GENERATOR
tFLTDLY
RQ
RESET
DOMINANT
FAULT
LATCH
S
ENABLE
MAX3286
MAX3296
FLTDLY
FAULT
FAULT
SHDNDRV
Figure 6. Simplified Safety Circuit Schematic
______________________________________________________________________________________ 11
11 Page |
Páginas | Total 28 Páginas | |
PDF Descargar | [ Datasheet MAX3296CGISEVKIT.PDF ] |
Número de pieza | Descripción | Fabricantes |
MAX3296CGISEVKIT | MAX3296 Shortwave or VCSEL (Common Cathode) Evaluation Kit | Maxim Integrated |
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