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PDF SY88432L Data sheet ( Hoja de datos )
| Número de pieza | SY88432L | |
| Descripción | 4.25 Gbps Transceiver | |
| Fabricantes | Micrel Semiconductor | |
| Logotipo |  |
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SY88432L
4.25 Gbps Transceiver with Integrated FP/DFP Laser
Diode Driver and Limiting Post Amplifier
General Description
The SY88432L is a low power transceiver device that
integrates a 4.25Gbps FP/DFB laser diode driver with a
wide-sensitivity limiting post amplifier. This low power
device is designed for use in fiber-optic optical modules
for multi-rate applications up to 4.25Gbps.
The SY88432L transmitter section can output up to
60mA of modulation current with fast rise and fall times
and is designed to be AC-coupled to the laser. The
transmitter output stage incorporates a transmit disable
feature and integrated 50Ω input impedance referenced
to VCC.
The receiver section’s limiting post amplifier connects to
a typical trans-impedance amplifier (TIA) to amplify the
incoming weak signal from the ROSA and outputs
normalized received data in CML format at the output.
The receiver offers a wide LOS (Loss Of Signal) Assert
range between 8mVPP to 40mVPP differential. A
programmable loss-of-signal level set pin (LOSLVL) sets
the sensitivity of the input amplitude detection. The LOS
or SD (signal-detect) is user selectable and the LOS/SD
signal can be fed back to the JAM input to implement
the SQUELCH function that maintains output stability
under a loss-of-signal condition. The receiver input
should be AC-coupled.
The SY88432L interfaces with Micrel’s highly advanced
optical module controller MIC3003 as an easy-to-use
chipset solution for CSFP/SFP/CSFF/SFF optical
module applications. The MIC3003 allows for both
modulation and bias current control, with automatic
power control (APC) and temperature compensation.
The SY88432L operates on a single 3.3V power supply
and is available in a 24 lead, 4x4mm QFN package.
All support documentation can be found on Micrel’s web
site at: www.micrel.com.
Features
Multi-rate operation up to 4.25Gbps
Single, wide range power supply: 3.3V 10%
Industrial temp range: -40°C to +85°C
MIC3003 compatible
Transmitter – FP/DFP Laser Diode Driver
Modulation current up to 60mA
- AC coupled laser diode modulation
- Voltage controlled modulation current
Rise/Fall times 65ps (typical)
TX Disable with internal 75kΩ pull down resistor
Integrated 50Ω input impedance to VCC
Receiver – Limiting Post Amplifier
Wide differential input range (10mVpp – 1800mVpp)
Programmable LOS level (LOSLVL) sensitivity
Wide LOS Assert range (8mVpp – 40mVpp)
- With 3.5dB typical electrical hysteresis
Selectable LOS or SD output
TTL compatible JAM input with internal pull up
Low-noise CML data outputs with integrated 50Ω
termination impedance
- Rise/Fall times 60ps (typical)
Low-noise CML data inputs with integrated 50Ω
termination impedance to internal reference VREF
Applications
Gigabit Ethernet
Fibre Channel – 1FC, 2FC, 4FC
SONET OC3/12/24/48 and with FEC
SDH STM1/4/8/16 and with FEC
Markets
Datacom / Telecom / Storage
Compact SFP/SFF Optical transceiver
SFP/SFF Optical transceiver
Wireless backhaul
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
July 2012
M9999-061312-A
[email protected] or (408) 955-1690
1 page  
Micrel, Inc.
SY88432L
Pin Description
Pin
Number
7, 10, 18
13, 16, 17
20, 23,
e-pad
Pin
Name
GND_T
VCC_T
GND_R
Type
Pin Function
Transmitter
Ground
Transmitter
Positive Supply
Rail
Receiver Ground
Transmitter Ground. Connect to the PCB ground plane.
Transmitter Voltage Supply. Bypass with a 0.1uF || 0.01uF low ESR capacitor as close to
VCC_T pin as possible.
Receiver Ground. Connect to the PCB ground plane. The e-pad must be connected to
the PCB ground plane using a via array to transfer the heat from the package to the PCB
ground plane.
Transmitter - Laser Diode Driver Truth Table
TXIN+
TXIN-
LH
HL
XX
Notes:
3. IMOD I MOD_OFF when MOD+ is HIGH.
4. Assuming that Laser is tied to MOD+
TXDIS
L
L
H
MOD+ (3)
H
L
H
MOD-
L
H
L
Laser Output (4)
L
H
L
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
July 2012
M9999-060512-A
5 Page 
Micrel, Inc.
Functional Description
Transmitter - Laser Diode Driver
The laser driver consists of three stages which include
the input buffer stage, a pre-driver stage where the
modulation current is set, and the output driver stage.
Input Buffer
The input stage is internally terminated to VCC with
50Ω impedances. The input signals should be routed
using 50Ω transmission lines and terminated with 50Ω
impedances at the load.
Pre-Driver / Modulation Control
This stage is used to control the modulation current
for the laser driver when an analog voltage between
0V to 1.2V is applied at the MODSET pin.
Output Driver
The output stage is an open-collector differential pair
capable of driving modulation currents up to 60mA. It
may be used single-ended or differentially. Specific
care must be taken to ensure that outputs are
terminated correctly for either mode of operation.
Figure 2 and 3 show input and output stages of the
driver.
Receiver - Post Amplifier
The post amplifier detects and amplifies signals with
data rates from 155Mbps and up to 4.25Gbps with
amplitudes as low as 10mVPP.
To reduce the noise at the output of the post amplifier
when the input signal is absent or lower than the
minimum detectable level set by LOSLVL, a JAM pin
is provided, which can be connected to LOS/SD
output to turn off the output buffer when LOS is
asserted or SD is de-asserted.
Input Amplifier/Buffer
Figure 4 shows a simplified schematic of the input
stage. The high-sensitivity of the input amplifier allows
signals as small as 10mVPP to be detected and
amplified. The input amplifier allows input signals as
large as 1800mVPP.
Figure 1 shows the allowed input voltage swing. Small
input signals below typically 12mVPP are linearly
amplified with a typical 38dB differential voltage gain.
For input signals larger than 12mVPP, the output signal
is limited to typically 800mVPP.
Output Buffer
The post amplifier CML output buffer is designed to
drive 50Ω lines and is internally terminated with 50Ω
SY88432L
to VCC. Figure 5 shows a simplified schematic of the
output stage which can be either AC-coupled (as
shown) or DC-coupled.
Loss-of-Signal
The post amplifier generates a selectable chatter-free
loss-of-signal (LOS) or signal detect (SD) open-
collector TTL output as shown in Figure 6. LOS/SD is
used to determine that the input amplitude is too small
to be considered as a valid input.
When the LOS function is selected (LOS/SD_S=0),
LOS/SD asserts high if the input amplitude falls below
the threshold set by LOSLVL and de-asserts low
otherwise.
If the SD function is selected (LOS/SD_S=1), LOS/SD
asserts low if the input amplitude falls below the
threshold set by LOSLVL and de-asserts high
otherwise.
LOS/SD can be fed back to the JAM input to maintain
output stability under a loss of signal condition. Jam
de-asserts low the true output signal without removing
the input signals.
Typically, 3dB LOS hysteresis is provided to prevent
chattering.
Loss/Signal Detect Selection
A pin (LOS/SD_S) is provided to select between LOS
(set to LOW) or SD (set to HIGH) function. It also
controls the internal circuitry of JAM input to follow
LOS/SD selection.
Loss-of-Signal-Level Set
A programmable LOS/SD level set pin (LOSLVL) sets
the threshold of the input amplitude detection.
Connecting an external resistor between VCC and
LOSLVL sets the voltage at LOSLVL. This voltage
ranges from VCC to VCC -1.3V. The external resistor
creates a voltage divider between VCC and VCC-1.3V,
as shown on Figure 7.
Hysteresis
The post amplifier provides typically 3.5dB LOS
electrical hysteresis, which is defined as 20log
(VINLOS-Assert / VINLOS-De-Assert). Since the relationship
between the voltage out of the ROSA to optical power
at its input is linear, the optical hysteresis will be
typically half of the electrical hysteresis reported in the
datasheet, but in practice, the ratio between electrical
and optical hysteresis is found to be within the range
1.5 to 1.8. Thus, 3.5dB electrical hysteresis will
correspond to an optical hysteresis within the range
1.6dB to 2dB.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
July 2012
M9999-060512-A
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet SY88432L.PDF ] | |
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