JSH-42L3AD3-20 JDS UNIPHASE, JSH-42L3AD3-20 Datasheet - Page 5

• Manufacturer Part Number: JSH-42L3AD3-20
• Manufacturer: JDS UNIPHASE

Specifications of JSH-42L3AD3-20

• Number Of Receivers: 1
• Operating Supply Voltage (typ): 3.3V
• Operating Temperature Classification: Commercial
• Operating Supply Voltage (max): 3.6V
• Operating Supply Voltage (min): 3V
• Operating Temperature (max): 85C
• Lead Free Status / Rohs Status: Compliant

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JSH-42L3AD3-20S / 64P0682
LW 4x/2x/1x FC SFP with DDM
Transmit Section
The input, an AC coupled differential data stream from the host, enters the AC Modulation section of the laser
driver circuitry where it modulates the output optical intensity of a semiconductor laser. The DC Drive circuit
incorporates an automatic power control (APC) loop which maintains the laser at the correct preset power
level. In addition, safety circuits in the DC Drive will shut off the laser, or guarantee safe launch power if a
fault is detected. The transceiver provides the AC coupling for the +Tx/-Tx lines. No AC coupling capacitors
are required on the host card for proper operation. There are two outputs from the transmitter section that
deliver signals proportional to the average transmitted optical power and also the laser average bias current.
These signals are digitized and processed within the transceiver for the Digital Diagnostic Monitoring feature.
Receive Section
The incoming modulated optical signal is converted to an electrical signal by the photoreceiver. This electrical
signal is then amplified and converted to a differential serial output data stream and delivered to the host. A
signal strength detector indicates whether light is present or not at the input to the photoreceiver. This signal
is provided to the host as a loss-of-signal (Rx_LOS) status line. The transceiver provides the AC coupling for
the +Rx/-Rx lines. No AC coupling capacitors are required on the host card for proper operation. There is an
output from the pre-amplifier in the photoreceiver that is proportional to the average optical power incident on
the photodiode. This signal is digitized and processed within the transceiver as part of the Digital Diagnostic
Monitoring feature.
Digital Diagnostic Monitoring
The digital diagnostic monitoring feature is compliant with document SFF-8472, “Digital Diagnostic Monitoring
Interface for Optical Transceivers” [5]. In addition to transmitted optical power, laser-bias current and received
optical power, there are also sensors for transceiver temperature and supply voltage which are all multiplexed
to the analog-to-digital converter. After the signals are digitized, they are processed and compared to alarm
levels for the optional alarm features and interrupts. The real-time values of each monitored parameter can
be read and used for evaluating the status of the link. Also, the alarm/warning bits can be used to provide
transceiver status or enable an interrupt notification. A user-writable non-volatile RAM scratch space for cus-
tomer use is limited to 100,000 write cycles.
Optional Monitor TX_FAULT Alarm/Warning Interrupt
The transceiver provides programmable Alarm/Warning Interrupt Enable bits. They are used by the trans-
ceiver to generate a TX_FAULT signal usable as an interrupt to the host for an alarm/warning condition. This
is an extension to the polling architecture of SFF-8472 and allows for interrupt driven host microcode. For a
complete description see section “Vendor Specific Digital Diagnostic Monitor TX_FAULT Alarm/Warning
Interrupt” on page 37.
JDSU Product Specification 21121822-001
October 2008
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