ds1863 Maxim Integrated Products, Inc., ds1863 Datasheet - Page 8

• Manufacturer Part Number: ds1863
• Description: Ds1863 Burst-mode Pon Controller With Integrated Monitoring
• Manufacturer: Maxim Integrated Products, Inc.

Burst-Mode PON Controller
With Integrated Monitoring
The DS1863 integrates the control and monitoring func-
tionality required to implement a PON system using
Maxim’s MAX3643 compact burst mode laser driver.
The compact laser driver solution offers a considerable
cost benefit by integrating control and monitoring fea-
tures in low power CMOS process, while leaving only
the high speed portions to the laser driver IC.
BIAS current is controlled by an Average Power Control
(APC) loop. The APC loop uses digital techniques to
overcome the difficulties associated with controlling
burst mode systems.
8
_____________________________________________________________________
I
2
C
COMMUNICATION
DISABLE INPUT
FAULT OUTPUT
Detailed Description
IN+
IN-
BEN+
BEN-
DIS
SDA
SCL
TX-F
TX-D
MONITOR/CONTROL CIRCUIT
COMPACT BURST MODE
LASER DRIVER
BURST MODE
MAX3643
DS1863
APC Control
MDOUT
BIAS+
MON1
MON2
MON3
OUT+
BIAS-
MDIN
OUT-
FETG
BMD
V
CC
The APC loop’s feedback is the monitor diode (BMD)
current, which is converted to a voltage using an exter-
nal resistor. The feedback voltage is compared to an 8-
bit scaleable voltage reference, which determines the
APC set point of the system. Scaling of the reference
voltage along with the modulation output can be uti-
lized to implement GPON power leveling.
The DS1863 has a Lookup Table to allow the APC set
point to change as a function of temperature to com-
pensate for Tracking Error (TE). The TE LUT (Table
05h), has 36 entries that determine the APC setting in
4°C windows between -40°C to +100°C.
Ranging of the APC DAC is possible by programming a
single byte in Table 02h.
3.3V
TRANSMIT POWER
RECEIVE POWER
Typical Operating Circuit