AFCT-5971LZ Broadcom

AFCT-5971LZ/ALZ Single Mode Laser Small Form Factor Fast Ethernet Transceivers Data Sheet Description Features The AFCT-5971LZ/ALZ are high performance, cost ef- Multisourced 2 x 5 package style with LC receptacle fective modules for serial optical data communications Single +3.3 V power supply applications specified for a signal rate of 125 Mbd. They Temperature range: are designed for fast ethernet applications and are also AFCT-5971LZ: 0 C to +70 C compatible with the EFM baseline 100-BASE-LX10 stan- AFCT-5971ALZ: -40C to +85C dard over dual single mode fiber. Wave solder and aqueous wash process compatible All modules are designed for single mode fiber and Manufactured in an ISO9002 certified facility operate at a nominal wavelength of 1300 nm. They in- Fully Class 1 CDRH/IEC 825 compliant corporate high performance, reliable, long wavelength IEEE 802.3ah Standard Compliant optical devices and proven circuit technology to give RoHS Compliant long life and consistent service. LVPECL compatible signal detect output The transmitter section of the AFCT-5971LZ/ALZ incor- Designed for EFM (Ethernet in the First Mile) baseline porates a 1300 nm Fabry Perot (FP) laser. The transmit- 100-BASE-LX10 performance over dual single mode ter has full IEC 825 and CDRH Class 1 eye safety. fiber The receiver section uses an MOVPE grown planar PIN Applications photodetector for low dark current and excellent re- sponsivity. Ethernet in the First Mile A pseudo-ECL compatible logic interface simplifies in - Fast Ethernet terface to external circuitry. These transceivers are supplied in the new industry standard 2 x 5 DIP style package with the LC fiber con - nector interface and is footprint compatible with SFF Multi Source Agreement (MSA).Functional Description Receiver Section Design These components will reduce the sensitivity of the re- The receiver section for the AFCT-5971LZ/ALZ con- ceiver as the signal bit rate is increased above 155 Mb/s. tains an InGaAs/InP photo detector and a preamplifier mounted in an optical subassembly. This optical subas- Noise Immunity sembly is coupled to a postamp/decision circuit on a circuit board. The design of the optical assembly is such The receiver includes internal circuit components to that it provides better than 14 dB Optical Return Loss filter power supply noise. However under some condi - (ORL). tions of EMI and power supply noise, external power supply filtering may be necessary (see Application Sec - The postampliefi r is ac coupled to the preamplifier as tion). illustrated in Figure 1. The coupling capacitors are large enough to pass the EFM test pattern at 125 MBd with- The Signal Detect Circuit out significant distortion or performance penalty. The signal detect circuit works by sensing the level of Figure 1 also shows a filter function which limits the the received signal and comparing this level to a refer- bandwidth of the preamp output signal. The filter is de - ence. The SD output is low voltage PECL. signed to bandlimit the preamp output noise and thus improve the receiver sensitivity. DATA OUT FILTER TRANS- LVPECL IMPEDANCE OUTPUT PRE- AMPLIFIER BUFFER AMPLIFIER DATA OUT GND LVPECL SIGNAL SD OUTPUT DETECT BUFFER CIRCUIT Figure 1. Receiver Block Diagram Functional Description Transmitter Section Design FP PHOTODIODE LASER (rear facet monitor) A schematic diagram for the transmitter is shown in Fig- ure 2. The AFCT-5971LZ/ALZ incorporates an FP laser as DATA LASER MODULATOR its optical source. All part numbers have been designed DATA LVPECL to be compliant with IEC 825 eye safety requirements INPUT under any single fault condition and CDRH under nor- mal operating conditions. The optical output is con- LASER BIAS trolled by a custom IC that detects the laser output via DRIVER the monitor photodiode. This IC provides both dc and ac current drive to the laser to ensure correct modula- tion, eye diagram and extinction ratio over temperature, supply voltage and operating life. LASER BIAS CONTROL Figure 2. Simplified Transmitter Schematic 2