afct-57d5anpz Avago Technologies, afct-57d5anpz Datasheet - Page 3

• Manufacturer Part Number: afct-57d5anpz
• Description: Digital Diagnostic Sfp Small Form Pluggable , Low Voltage 3.3 V 25km, 1310nm Dfb, 8.5/4.25/2.125 Gbd Fibre Channel Rohs Compliant Digital Diagnostic Optical Transceiver
• Manufacturer: Avago Technologies

Figure 1. Transceiver functional diagram.
Transmitter Section
The transmitter section includes the Transmitter Optical
SubAssembly (TOSA) and laser driver circuitry. The TOSA,
containing an 1310nm DFB (Distributed Feedback Laser)
light source, is located at the optical interface and mates
with the LC optical connector. The TOSA is driven by a
custom IC which uses the incoming differential high speed
logic signal to modulate the laser diode driver current.
This Tx laser driver circuit regulates the optical power at
a constant level provided the incoming data pattern is dc
balanced (8B/10B code, for example).
Transmit Disable (Tx_Disable)
The AFCT-57D5ANPZ accepts a TTL and CMOS compat-
ible transmit disable control signal input (pin 3) which
shuts down the transmitter optical output. A high signal
implements this function while a low signal allows normal
transceiver operation. In the event of a fault (e.g. eye safety
circuit activated), cycling this control signal resets the
module as depicted in Figure 4. An internal pull up resistor
disables the transceiver transmitter until the host pulls
the input low. Host systems should allow a 10 ms interval
between successive assertions of this control signal.
Tx_Disable can also be asserted via the two-wire serial
interface (address A2h, byte 110, bit 6) and monitored
(address A2h, byte 110, bit 7).
The contents of A2h, byte 110, bit 6 are logic OR’d with
hardware Tx_Disable (pin 3) to control transmitter
operation.
3
OPTICAL INTERFACE
LIGHT FROM FIBER
LIGHT TO FIBER
RECEIVER
TRANSMITTER
PHOTO-DETECTOR
VCSEL
CONTROLLER & MEMORY
AMPLIFICATION
& QUANTIZATION
Transmit Fault (Tx_Fault)
A catastrophic laser fault will activate the transmitter
signal, TX_FAULT, and disable the laser. This signal is an
open collector output (pull-up required on the host board).
A low signal indicates normal laser operation and a high
signal indicates a fault. The TX_FAULT will be latched high
when a laser fault occurs and is cleared by toggling the
TX_DISABLE input or power cycling the transceiver. The
transmitter fault condition can also be monitored via the
two-wire serial interface (address A2, byte 110, bit 2).
Eye Safety Circuit
The AFCT-57D5ANPZ provides Class 1 (single fault tolerant)
eye safety by design and has been tested for compliance
with the requirements listed in Table 1. The eye safety
circuit continuously monitors the optical output power
level and will disable the transmitter upon detecting an
unsafe condition beyond the scope of Class 1 certification.
Such unsafe conditions can be due to inputs from the host
board (Vcc fluctuation, unbalanced code) or a fault within
the transceiver.
CIRCUITRY
DRIVER &
SAFETY
LASER
RD+ (RECEIVE DATA)
RD- (RECEIVE DATA)
Rx LOSS OF SIGNAL
MOD-DEF2 (SDA)
MOD-DEF1 (SCL)
MOD-DEF0
TX_DISABLE
TD+ (TRANSMIT DATA)
TD- (TRANSMIT DATA)
TX_FAULT
ELECTRICAL INTERFACE