User Manual

DS1862
XFP Laser Control and Digital Diagnostic IC
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Power-Supply Decoupling
To achieve best results, it is recommended that the
power supply is decoupled with a 0.01µF or a 0.1µF
capacitor. Use high-quality, ceramic, surface-mount
capacitors, and mount the capacitors as close as pos-
sible to the V
CC2
/V
CC3
and GND pins to minimize lead
inductance.
SDA and SCL Pullup Resistors
SDA is an open-collector bidirectional data pin on the
DS1862 that requires a pullup resistor to realize high
logic levels. Either an open-collector output with a
pullup resistor or a push-pull output driver can be uti-
lized for the SCL input. Pullup resistor values should be
chosen to ensure that the rise and fall times listed in the
AC Electrical Characteristics are within specification.
*ADDITIONAL MONITORS NOT USED IN THIS EXAMPLE.
SDA
SCL
4.7kΩ
RX-LOS
MOD-NR
V
CC2
TX-D
INTERRUPT
MOD-DESEL
V
CC3
EN1
SC-TX-LOS
GND
EN2
BMD
BIASSET
MODSET
FETG
BIASMON
RSSI
SC-RX-LOL
SC-RX-LOS
THRSET
AUX1MON
AUX2MON
P-DOWN/RST
HOST
1.8V 3.3V
3.3V
0.1µF
0.1µF
BIASSET
MODSET
MON
LASER
DRIVER
10nF
OUT
LIMITING
AMP
LOS
LOL
FCTL2
FCTL1
VTH
LOS
FCTL2
FCTL1
EQUALIZER
RECEIVER CURRENT SENSE (VOLTAGE)
TX-DISABLE
TX-DISABLE
DISABLE
1nF
*
1kΩ
DS1862
MAX3975
MAX3991
MAX3992
4.7kΩ
3.3V
10kΩ
3.3V
10kΩ
3.3V
10kΩ
3.3V
Typical Operating Circuit