1.25Gbps 120km SFP Optical Transceiver - Fiber Optic Cabling Management
1.25Gbps 40km SFP Optical Transceiver,DDM


The SFP transceivers are high performance, cost-effective modules supporting dual data-rate of 1.25Gbps and 120km transmission distance with SMF. The transceiver consists of three sections: a DFB laser transmitter, a PIN photodiode integrated with a trans-impedance preamplifier (TIA), and an MCU control unit. All modules satisfy class I laser safety requirements. The transceivers are compatible with SFP Multi-Source Agreement (MSA) and SFF-8472. For further information, please refer to SFP MSA.



  • Dual data-rate of 1.25Gbps operation
  • 1550nm DFB laser and PIN photodetector for 120km transmission
  • Compliant with SFP MSA and SFF-8472 with duplex LC receptacle
  • Digital Diagnostic Monitoring:
  • Internal Calibration or External Calibration
  • Compatible with RoHS
  • Compatible with CE
  • +3.3V single power supply
  • Operating case temperature:
    • Standard: 0 to +70°C
    • Industrial: -40 to +85°C


  • Gigabit Ethernet
  • Fiber Channel
  • Switch to Switch interface
  • Switched backplane applications
  • Router/Server interface
  • Other optical transmission systems

Module Block Diagram


Absolute Maximum Rating

Power Supply VoltageVCC-0.5+4.0V
Storage TemperatureTc-40+85C
Relative HumidityRH585%

Recommended Operating Environment

Operating Case TemperatureStandardTc0+70°C
Power Supply VoltageVcc3.133.33.47V
Power Supply CurrentIcc300mA
Data Rate1.25Gbps

Optical and Electrical Characteristics

Centre Wavelengthλc148015501580nm
Spectral Width (RMS)σ1nm
Side Mode Suppression RatioSMSR30dB
Average Output PowerPout05dBm1
Extinction RatioER9dB
Optical Rise/Fall Time (20%~80%)tr/tf0.26ns
Data Input Swing DifferentialVIN4001800mV2
Input Differential ImpedanceZIN90100110Ω
TX DisableDisable2.0VccV
TX FaultFault2.0VccV
Centre Wavelengthλc12601580nm
Receiver Sensitivity-30dBm3
Receiver Overload-9dBm3
LOS De-AssertLOSD-32dBm
LOS AssertLOSA-35dBm
LOS Hysteresis0.54.5dB
Data Output Swing DifferentialVout4001800mV4


  1. The optical power is launched into SMF.
  2. PECL input, internally AC-coupled and terminated.
  3. Measured with a PRBS 27-1 test pattern @1250Mbps, BER ≤1×10-12.
  4. Internally AC-coupled.

Timing and Electrical

Tx Disable Negate Timet_on1ms
Tx Disable Assert Timet_off10µs
Time to Initialize, including Reset of Tx Faultt_init300ms
Tx Fault Assert Timet_fault100µs
Tx Disable to Resett_reset10µs
LOS Assert Timet_loss_on100µs
LOS De-assert Timet_loss_off100µs
Serial ID Clock Ratef_serial_clock400KHz
MOD_DEF (0:2)-HighVH2VccV
MOD_DEF (0:2)-LowVL0.8V


Temperature0 to +70°C±3°CInternal / External
-20 to +85
Voltage3.0 to 3.6V±3%Internal / External
Bias Current0 to 100mA±10%Internal / External
TX Power0 to +5dBm±3dBInternal / External
RX Power-30 to -9dBm±3dBInternal / External

Digital Diagnostic Memory Map

The transceivers provide serial ID memory contents and diagnostic information about the present operating conditions by the 2-wire serial interface (SCL, SDA).

The diagnostic information with internal calibration or external calibration all are implemented, including received power monitoring, transmitted power monitoring, bias current monitoring, supply voltage monitoring and temperature monitoring.

The digital diagnostic memory map specific data field defines as following.

Pin Definition

PinSignal NameDescriptionPlug Seq.Notes
1VEETTransmitter Ground1
2TX FAULTTransmitter Fault Indication3Note 1
3TX DISABLETransmitter Disable3Note 2
4MOD_DEF(2)SDA Serial Data Signal3Note 3
5MOD_DEF(1)SCL Serial Clock Signal3Note 3
6MOD_DEF(0)TTL Low3Note 3
7Rate SelectNot Connected3
8LOSLoss of Signal3Note 4
9VEERReceiver ground1
10VEERReceiver ground1
11VEERReceiver ground1
12RD-Inv. Received Data Out3Note 5
13RD+Received Data Out3Note 5
14VEERReceiver ground1
15VCCRReceiver Power Supply2
16VCCTTransmitter Power Supply2
17VEETTransmitter Ground1
18TD+Transmit Data In3Note 6
19TD-Inv. Transmit Data In3Note 6
20VEETTransmitter Ground1

Notes: Plug Seq.: Pin engagement sequence during hot plugging.

  1. TX Fault is an open collector output, which should be pulled up with a 4.7k~10kΩ resistor on the host board to a voltage between 2.0V and Vcc+0.3V. Logic 0 indicates normal operation; Logic 1 indicates a laser fault of some kind. In the low state, the output will be pulled to less than 0.8V.
  2. TX Disable is an input that is used to shut down the transmitter optical output. It is pulled up within the module with a 4.7k~10kΩ resistor. Its states are:

Low (0 to 0.8V): Transmitter on

(>0.8V, < 2.0V): Undefined

High (2.0 to 3.465V): Transmitter Disabled

Open: Transmitter Disabled

  1. Mod-Def 0,1,2. These are the module definition pins. They should be pulled up with a 4.7k~10kΩ resistor on the host board. The pull-up voltage shall be VccT or VccR.

Mod-Def 0 is grounded by the module to indicate that the module is present

Mod-Def 1 is the clock line of the two-wire serial interface for serial ID

Mod-Def 2 is the data line of the two-wire serial interface for serial ID

  1. LOS is an open collector output, which should be pulled up with a 4.7k~10kΩ resistor. Pull up voltage between 2.0V and Vcc+0.3V. Logic 1 indicates loss of signal; Logic 0 indicates normal operation. In the low state, the output will be pulled to less than 0.8V.
  2. RD-/+: These are the differential receiver outputs. They are internally AC-coupled 100 differential lines which should be terminated with 100Ω (differential) at the user SERDES.
  3. TD-/+: These are the differential transmitter inputs. They are internally AC-coupled, differential lines with 100Ω differential termination inside the module.


Regulatory Compliance

LinkWell SFP transceiver is designed to be Class I Laser safety compliant and is certified per the following standards:

Laser SafetyFDACDRH 21 CFR 1040 and Laser Notice No. 50
Product SafetyULUL and CUL EN60950-2: 2007
Environmental protectionSGSRoHS Directive 2002/95/EC
EMCCCICEN 55022: 2006+A1: 2007

EN 55024: 1998+A1+A2: 2003


Ordering Information

Part NumberProduct Description
LW-SFP-1512-120DSFP, 1550nm, 1.25Gbps, 120km, 0ºC ~ +70ºC, With Digital Diagnostic Monitoring
LW-SFP -1512-120DISFP, 1550nm, 1.25Gbps, 120km, -40ºC ~ +85ºC, With Digital Diagnostic Monitoring


  1. Small Form Factor Pluggable (SFP) Transceiver Multi-Source Agreement (MSA), September 2000.
  2. Telcordia GR-253-CORE and ITU-T G.957 Specifications.

Important Notice

Performance figures, data and any illustrative material provided in this data sheet are typical and must be specifically confirmed in writing by LinkWell before they become applicable to any particular order or contract. In accordance with the LinkWell policy of continuous improvement specifications may change without notice.

The publication of information in this data sheet does not imply freedom from patent or other protective rights of LinkWell or others. Further details are available from any LinkWell sales representative.