SY88904 Datasheet, PDF (1/8 Pages) Micrel Semiconductor – FIBER OPTIC MODULE CONTROLLER WITH APC

Micrel, Inc.
FIBER OPTIC MODULE
CONTROLLER WITH APC
SY88904
SY88904
FEATURES
DESCRIPTION
s DC bias current adjustable to 25mA
s Buffered Loss-of-Signal output when used with
SY88903
s Controlled laser diode turn on
s Laser diode over-current detect
s Monitor diode power control circuit
s Laser diode driver enable
s Designed for use with SY88902 and SY88903
s Single power supply
s Available in 16-pin MSOP
APPLICATIONS
s Controller for High Speed Optical Data Transmission
s 1.25Gbps Gigabit Ethernet
s 531 Mbps and 1062Mbps Fibre Channel
s 622Mbps SONET
s Gigabit Interface Converter
The SY88904 is an integrated controller for the SY88902
Laser Driver and SY88903 Laser Receiver that provides
power control and system interface functions for a complete
module solution. The SY88904 is designed to provide the
laser diode with an independent DC threshold current (IBIAS)
source to assure optimum laser diode performance. It has
special safety features which disable the currents to the
laser diode if certain faults are detected in the module. The
SY88904 also provides buffered Loss-of-Signal (LOS) output
in open collector level. The device is designed for fast and
accurate calibration of the laser diode as well as deriving
the control signals for system integration.
The SY88904 provides for delayed turn on of the laser
diode on system start up, chatter-free Loss-of-Signal, Low
VCC detect and laser diode over-current situations. Once
the optimal operating point is determined and set for a
specific laser diode, the threshold current (IBIAS) is designed
to automatically compensate for laser diode aging and
module temperature.
BLOCK DIAGRAM
TTL
LOSIN
LOSOUT
PECL
PECL
TX_Out
OC
TX_Fault
TTL
TX_Disable
Fault
Detect
Circuit
II_LIMIT
MD_Low
40X
VCC DET
VCC DET
4.75
-
+
-
VREF 3
+
-
+
VREF 2
VREF 4
RWIN
IBIAS SET
IBIAS FB
IPIN SET
ILIMIT SET
IBIAS
MD
VCC
GND
VREF
M9999-081005
[e-mail] or [phone]
1
Rev.: B Amendment: /0
Issue Date: August 2005