Specifications
The 1.25Gbps Bi-Directional SFP Optical Transceiver is designed for ultra-long-distance communication over single-mode fiber (SMF) up to 120 kilometers. Utilizing LC connectors, the module integrates a 1490nm DFB laser with a 1550nm APD receiver or a 1550nm DFB laser with a 1490nm APD receiver, depending on the configuration. It supports a single +3.3V power supply and a data rate of 1.25Gbps, making it ideal for Ethernet, telecom, and Fiber Channel applications. The module is compliant with IEC-60825 laser safety standards and RoHS directives, ensuring safety and environmental responsibility.
This transceiver operates reliably within a temperature range of 0°C to 70°C for commercial applications and -40°C to 85°C for industrial use, with a power dissipation of only 1W. The transmitter offers an average output power of 0 to +5dBm, with an extinction ratio between 9dB and 15dB, while the receiver provides a sensitivity of -32dBm and an overload threshold of -7dBm. Advanced diagnostic features, including Loss of Signal (LOS) detection, enhance performance monitoring and fault management, making the module a dependable solution for long-distance, high-speed optical communication.
These BiDi SFP modules provide cost-effective long-haul connectivity over a single strand of SMF, supporting Ethernet, Fibre Channel, and telecom networks. Operating from a single +3.3 V supply, they offer LVPECL-compatible I/O, low EMI, and high ESD protection. The devices meet IEC-60825 laser safety and RoHS compliance standards.
Absolute Maximum Ratings
| Parameter | Symbol | Min | Max | Units |
|---|---|---|---|---|
| Storage temperature | Tst | −40 | +85 | °C |
| Supply voltage | Vcc | 0 | +3.6 | V |
| Operating relative humidity | RH | 5 | 95 | % |
Operating Conditions
| Parameter | Symbol | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Supply voltage | Vcc | 3.15 | 3.3 | 3.45 | V |
| Case temperature (Commercial) | Tc | 0 | — | +70 | °C |
| Case temperature (Industrial) | — | −40 | — | +85 | °C |
| Power dissipation | — | — | — | 1 | W |
| Data rate | — | — | 1.25 | — | Gbps |
Optical Characteristics (0 °C to +70 °C, Vcc = 3.3 V)
Transmitter
| Parameter | Variant | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Center wavelength | Tx 1490 | 1480 | 1490 | 1500 | nm |
| Center wavelength | Tx 1550 | 1540 | 1550 | 1560 | nm |
| RMS spectral width | Tx 1490 / Tx 1550 | — | — | 1 | nm |
| Average output power | Tx 1490 / Tx 1550 | 0 | — | +5 | dBm |
| Extinction ratio | — | 9 | — | 15 | dB |
| Rise/fall time (20–80%) | — | — | — | 0.26 | ns |
| Total jitter | — | — | — | 0.43 | UI |
| Optical eye: IEEE 802.3z and ANSI Fibre Channel compatible. |
Receiver
| Parameter | Variant | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Center wavelength | Rx 1550 | 1500 | 1550 | 1600 | nm |
| Center wavelength | Rx 1490 | 1440 | 1490 | 1540 | nm |
| Sensitivity (Rsen) | — | — | — | −32 | dBm |
| Overload (Rov) | — | −7 | — | — | dBm |
| Return loss | — | 12 | — | — | dB |
| LOS assert (LOSA) | — | −45 | — | — | dBm |
| LOS de-assert (LOSD) | — | — | — | −32 | dBm |
| LOS hysteresis | — | 0.5 | — | 5 | dB |
BiDi pair mapping
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CT-SFP-BX-120U: 1490 nm DFB Tx / 1550 nm APD Rx
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CT-SFP-BX-120D: 1550 nm DFB Tx / 1490 nm APD Rx.
Electrical Characteristics (0 °C to +70 °C, Vcc = 3.3 V)
Transmitter I/O
| Parameter | Symbol | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Input differential impedance | Zin | 90 | 100 | 110 | Ω |
| Data input swing (diff.) | Vin | 500 | — | 2400 | mV |
| TX Disable — High (disable) | — | 2.0 | — | Vcc | V |
| TX Disable — Low (enable) | — | 0 | — | 0.8 | V |
| TX Fault — Assert | — | 2.0 | — | Vcc | V |
| TX Fault — De-assert | — | 0 | — | 0.8 | V |
Receiver I/O
| Parameter | Symbol | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Output differential impedance | Zout | — | 100 | — | Ω |
| Data output swing (diff.) | Vout | 370 | — | 2000 | mV |
| Rx_LOS — Assert | — | 2.0 | — | Vcc | V |
| Rx_LOS — De-assert | — | 0 | — | 0.8 | V |
EEPROM & Pins (summary)
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EEPROM (A0h): includes SFP identifier, LC connector, 1.25 Gbps nominal BR, LOS/TX_DISABLE/TX_FAULT support, wavelength codes (1490/1550 nm), vendor PN/revision/date fields.
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Pin functions: TX Disable (input with internal pull-up), TX Fault (open collector), LOS (open collector), MOD-DEF[0:2] for 2-wire serial ID. TD± and RD± are AC-coupled differential 100 Ω pairs.