NLT-25-80-BA DS02-183 METR-1 2-23-03final.fm

NetLight

NLT25-80-BA 2.5 Gb/s 1550 nm Laser Transceiver

for Extended Long Reach

Preliminary Data Sheet, Rev. 1

February 2003

TriQuint Optoelectronics

Available in a small form-factor, metal package with LC recep-
tacle connector, the NLT25-80-BA transceiver is a high-perfor-
mance, cost-effective, optical transceiver for SONET/SDH
applications.

Features

Multisource agreement compliant SFF package

LC duplex receptacle

Metal package for superior EMI performance

Uncooled 1550 nm DFB laser transmitter with
automatic output power control

Transmitter disable input

Wide dynamic range receiver with InGaAs PIN
photodetector

LVTTL signal-detect output

Low power dissipation

Single 3.3 V power supply

Built-in APD dc-dc converter

ac-coupled LVPECL/CML compatible data inputs
and CML compatible data outputs

Operating temperature range of 0

°C to 70 °C

Telecom reliability (GR-468-CORE RT)

Wave solderable and aqueous wash compatible

Applications

SONET OC-48 LR-2, SDH L-16.2 applications

High-speed optical data interface for shelf-to-shelf
interconnect

Description

The NLT25-80-BA transceiver is a high-speed, cost-
effective optical transceiver that is intended for
2.488 Gb/s shelf-to-shelf optical interconnect appli-
cations, as well as SONET OC-48 LR-2 and
SDH L-16.2 80 km applications. The transceiver fea-
tures TriQuint optics and is packaged in a narrow-
width metal housing with an LC duplex receptacle.
The 20-pin package pinout conforms to a multisource
transceiver agreement.

The transmitter features the ability to interface to
both LVPECL and CML differential logic level data
inputs via ac-coupled inputs. The transmitter also
features an LVTTL logic level disable input and laser
bias and back-facet monitor outputs. The receiver
features ac-coupled differential CML logic level data
outputs, an LVTTL logic level signal-detect output,
and direct access to the APD bias input for photocur-
rent monitoring purposes.

riQ

For additional information and latest specifications, see our website: www.triquint.com

NetLight NLT25-80-BA 2.5 Gb/s 1550 nm Laser Transceiver

Preliminary Data Sheet, Rev. 1

for Extended Long Reach

February 2003

Absolute Maximum Ratings

Stresses in excess of the absolute maximum ratings can cause permanent damage to the device. These are abso-
lute stress ratings only. Functional operation of the device is not implied at these or any other conditions in excess
of those given in the operations sections of the data sheet. Exposure to absolute maximum ratings for extended
periods can adversely affect device reliability.

Table 1. Absolute Maximum Ratings

Pin Information

Figure 1. Top View of the NLT25-80-BA Transceiver, 20-Pin Configuration

Parameter

Symbol

Min

Max

Unit

Supply Voltage

Operating Case Temperature Range

°C

Storage Temperature Range

°C

Lead Soldering Temperature/Time

260/10

°C/s

Operating Wavelength Range

1.2

1.6

µm

Table 2. Receiver Pin Descriptions

Pin #

Symbol

Functional Description

Logic Family

Mounting Studs. The mounting studs are provided for
transceiver mechanical attachment to the circuit board. The
mounting studs must be connected to the equipment chassis
ground.

Photodetector Bias Input. This lead supplies bias for the
APD.

EER

Receiver Signal Ground.

EER

Receiver Signal Ground.

NIC

No Internal Connection.

NIC

No Internal Connection.

EER

Receiver Signal Ground.

CCR

Receiver Power Supply.

Signal Detect.
Normal operation: logic one output.
Fault condition: logic zero output.

LVTTL

Received

Data

Out.

ac-coupled CML

RD+

Received Data Out.

ac-coupled CML

For additional information and latest specifications, see our website: www.triquint.com

Preliminary Data Sheet, Rev. 1

NetLight NLT25-80-BA 2.5 Gb/s 1550 nm Laser Transceiver

February 2003

for Extended Long Reach

Pin Information

(continued)

Table 3. Transmitter Pin Descriptions

Pin #

Symbol

Functional Description

Logic Family

CCT

Transmitter Power Supply.

EET

Transmitter Signal Ground.

Transmitter Disable.

LVTTL

TD+

Transmitter Data In. An internal 50

termination is pro-

vided consisting of a 100

resistor between the TD+ and

TD pins.

ac-coupled

PECL/CML

Transmitter

Data

In. See TD+ pin for terminations.

ac-coupled

PECL/CML

EET

Transmitter Signal Ground.

MON

()

Laser Diode Bias Current Monitor--Negative End.
Optional feature. If feature is not used, do not connect.
The laser bias current is accessible as a dc voltage by mea-
suring the voltage developed across pins 17 and 18.

MON

(+)

Laser Diode Bias Current Monitor--Positive End.
Optional feature. If feature is not used, do not connect.
See pin 17 description.

MON

()

Laser Diode Optical Power Monitor--Negative End.
Optional feature. If feature is not used, do not connect. The
back-facet diode monitor current is accessible as a voltage
proportional to the photocurrent through a 200

resistor

between pins 19 and 20.

MON(

Laser Diode Optical Power Monitor--Positive End.
Optional feature. If feature is not used, do not connect.
See pin 19 description.

Electrostatic Discharge

Caution: This device is susceptible to damage as a

result of electrostatic discharge (ESD).
Take proper precautions during both han-
dling and testing. Follow EIA

Standard

EIA-625.

Although protection circuitry is designed into the
device, take proper precautions to avoid exposure to
ESD.

TriQuint employs a human-body model (HBM) for ESD
susceptibility testing and protection-design evaluation.
ESD voltage thresholds are dependent on the critical
parameters used to define the model. A standard HBM
(resistance = 1.5 k

, capacitance = 100 pF) is widely

used and, therefore, can be used for comparison pur-
poses. The HBM ESD threshold established for the
NLT25-80-BA is ±1000 V.

Application Information

The receiver section is a highly sensitive fiber-optic
receiver. Although the data outputs are digital logic lev-
els (CML), the device should be thought of as an ana-
log component. When laying out system application
boards, the transceiver should receive the same type
of consideration given to a sensitive analog compo-
nent.

Printed-Wiring Board Layout Considerations

A fiber-optic receiver employs a very high gain, wide-
bandwidth transimpedance amplifier. This amplifier
detects and amplifies signals that are only tens of nA in
amplitude when the receiver is operating near its sensi-
tivity limit. Any unwanted signal currents that couple
into the receiver circuitry cause a decrease in the
receiver's sensitivity and can also degrade the perfor-
mance of the receiver's signal-detect (SD) circuit.

NetLight NLT25-80-BA 2.5 Gb/s 1550 nm Laser Transceiver

Preliminary Data Sheet, Rev. 1

for Extended Long Reach

February 2003

4
4

For additional information and latest specifications, see our website: www.triquint.com

Application Information

(continued)

Printed-Wiring Board Layout Considerations

(continued)

To minimize the coupling of unwanted noise into the
receiver, careful attention must be given to the printed-
wiring board.

At a minimum, a double-sided printed-wiring board
(PWB) with a large component-side ground plane
beneath the transceiver must be used. In applications
that include many other high-speed devices, a multi-
layer PWB is highly recommended. This permits the
placement of power and ground on separate layers,
which allows them to be isolated from the signal lines.

Multilayer construction also permits the routing of sen-
sitive signal traces away from high-level, high-speed
signal lines. To minimize the possibility of coupling
noise into the receiver section, high-level, high-speed
signals such as transmitter inputs and clock lines
should be routed as far away as possible from the
receiver pins.

Noise that couples into the receiver through the power
supply pins can also degrade performance. It is recom-
mended that the pi filter, shown in Figure 3, be used for
both the transmitter and receiver power supplies.

Data and Signal-Detect Outputs

Due to the high switching speeds of CML outputs,
transmission line design must be used to interconnect
components. To ensure optimum signal fidelity, both
data and clock outputs should be terminated identically.
The signal lines connecting the data outputs to the next
device should be equal in length and have matched
impedances. Controlled-impedance stripline or micro-
strip construction must be used to preserve the quality
of the signal into the next component and to minimize
reflections back into the receiver, which could degrade
its performance. Excessive ringing due to reflections
caused by improperly terminated signal lines makes it
difficult for the component receiving these signals to
decipher the proper logic levels and can cause transi-
tions to occur where none were intended. Also, by min-
imizing high-frequency ringing, possible EMI problems
can be avoided.

The signal-detect output is positive LVTTL logic. A logic
low at this output indicates that the optical signal into
the receiver has been interrupted or that the light level
has fallen below the minimum signal-detect threshold.
This output should not be used as an error rate indica-
tor since its switching threshold is determined only by
the magnitude of the incoming optical signal.

Figure 2. Data and Clock Output Logic Level

Definitions

Transceiver Processing

When the process plug is placed in the transceiver's
optical port, the transceiver and plug can withstand
normal wave soldering and aqueous spray cleaning
processes. However, the transceiver is not hermetic,
and should not be subjected to immersion in cleaning
solvents. The transceiver case should not be exposed
to temperatures in excess of 125 °C. The transceiver
pins can be wave soldered at 260 °C for up to 10 sec-
onds. The process plug should only be used once.
After removing the process plug from the transceiver, it
must not be used again as a process plug; however, if
it has not been contaminated, it can be reused as a
dust cover.

DATA/CLOCK

SINGLE ENDED

DATA/CLOCK

DIFFERENTIAL

For additional information and latest specifications, see our website: www.triquint.com

Preliminary Data Sheet, Rev. 1

NetLight NLT25-80-BA 2.5 Gb/s 1550 nm Laser Transceiver

February 2003

for Extended Long Reach

Transceiver Optical and Electrical Characteristics

1. 50

load, measured single ended. Differential operation is necessary for optimum performance. (See Figure 2 for a visual representation.)

2. TTL compatible interface.

1. 2

1 PRBS with a BER of 1 x 10

2. 50

load, measured single ended. Differential operation is necessary for optimum performance. (See Figure 2 for a visual representation.)

3. TTL compatible interface.

Table 4. Transmitter Optical and Electrical Characteristics (T

= 0

°C to 70 °C, V

= 3.135 V--3.465 V.

All parameters must meet the specifications over the entire lifetime.)

Parameter

Symbol

Min

Max

Unit

Average Optical Output Power

dBm

Optical Wavelength

1500

1580

Spectral Width

20dB

Dispersion Penalty

Side-mode Suppression ratio

SMSR

Dynamic Extinction Ratio

EXT

8.2

Output Optical Eye

Compliant with SONET GR-253-CORE and

ITU-T G.957 Eye Mask Requirements

Power Supply Current

CCT

150

Input Data Voltage--Single Ended

Input Data Voltage--Differential

p-p

150
300

800

1600

mVp-p
mVp-p

Transmit Disable Voltage

Vcc 0.9

Vcc

Transmit Enable Voltage

+ 0.8

Laser Bias Voltage

BIAS

0.0

0.7

Laser Back-facet Monitor Voltage

0.01

0.2

Table 5. Receiver Optical and Electrical Characteristics (T

= 0

°C to 70 °C, V

= 3.135 V--3.465 V)

Parameter

Symbol

Min

Max

Unit

Average Sensitivity

dBm

Maximum Input Power

MAX

dBm

Power Supply Current

CCR

150

Output Data Voltage--Single Ended

Output Data Voltage--Differential

OUT

p-p

OUT

p-p

300
600

500

1000

mVp-p
mVp-p

Signal-detect Switching Threshold

Assert
Deassert

LSTD

LSTI

45
45

29.0
28.5

dBm
dBm

Signal-detect Hysteresis

HYS

0.5

Signal-detect Voltage

Low
High

0.0
2.4

0.8

V
V

Signal-detect Response Time

SDRT

100

µs

Part Number NLT25-80-BA

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