Specifications
The CT-SFP-BX-40U and CT-SFP-BX-40D are high-performance bi-directional (BIDI) SFP optical transceivers capable of transmitting data at 1.25Gbps over single-mode fiber (SMF) distances of up to 40 kilometers. These transceivers utilize a 1310nm FP laser and 1550nm PIN photodetector in the CT-SFP-BX-40U, and a 1550nm DFB laser with 1310nm PIN photodetector in the CT-SFP-BX-40D. Featuring an SFP package with LC connectors, these modules are designed for Ethernet, Telecom, and Fiber Channel applications. They are fully compliant with IEC-60825 laser safety standards and RoHS requirements.
With a single +3.3V power supply, LVPECL-compatible data interfaces, low EMI, and superior ESD protection, these transceivers ensure reliable and robust operation in both commercial and industrial environments. They support an operating temperature range of -40°C to +85°C for industrial-grade and 0°C to +70°C for commercial-grade devices. Optical performance includes precise wavelength control at 1310nm/1550nm, high extinction ratios, and excellent sensitivity, making them ideal for long-distance and high-speed optical communication systems.
These BiDi SFP modules are optimized for Ethernet, Fibre Channel, and telecom networks requiring cost-effective long-reach single-fiber solutions. They operate from a single +3.3 V supply, provide LVPECL-compatible I/O, and incorporate low EMI with strong ESD protection. The modules are IEC-60825 laser-safety certified and RoHS compliant.
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 1310 | 1260 | 1310 | 1360 | nm |
| Center wavelength | Tx 1550 | 1540 | 1550 | 1560 | nm |
| RMS spectral width | Tx 1310 | — | — | 4 | nm |
| RMS spectral width | Tx 1550 | — | — | 1 | nm |
| Average output power | Tx 1310 | −5 | — | 0 | dBm |
| Average output power | Tx 1550 | −5 | — | 0 | dBm |
| Extinction ratio | — | 10 | — | 15 | dB |
| Rise/fall time (20–80%) | — | — | — | 0.26 | ns |
| Total jitter | — | — | — | 0.43 | UI |
| Optical eye: IEEE 802.3z and ANSI Fibre Channel compliant. |
Receiver
| Parameter | Variant | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Center wavelength | Rx 1550 | 1500 | 1550 | 1600 | nm |
| Center wavelength | Rx 1310 | 1260 | 1310 | 1360 | nm |
| Sensitivity (Rsen) | — | — | — | −24 | dBm |
| Overload (Rov) | — | −3 | — | — | dBm |
| Return loss | — | 12 | — | — | dB |
| LOS assert (LOSA) | — | −36 | — | — | dBm |
| LOS de-assert (LOSD) | — | — | — | −24 | dBm |
| LOS hysteresis | — | 0.5 | — | 5 | dB |
BiDi pair mapping
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CT-SFP-BX-40U: 1310 nm FP Tx / 1550 nm PIN Rx
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CT-SFP-BX-40D: 1550 nm DFB Tx / 1310 nm PIN 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, and wavelength codes for 1310/1550 nm operation.
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Key pins: 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.
