Datasheet

DS1886
SFP and PON ONU Controller
with Digital LDD Interface
19Maxim Integrated
Detailed Description
The DS1886 integrates the control and monitoring func-
tionality required to implement an SFP or PON ONU
system using the Maxim MAX3710 or other compatible
laser driver and limiting amplifier. Key components of the
DS1886 are shown in the Block Diagram and described
in subsequent sections.
Monitors and Fault Detection
Monitors
The DS1886 monitors five ADC channels. This monitoring
combined with the alarm enables (A2h Table 01h/05h)
determines when/if the DS1886 turns off the MAX3710
DACs and triggers the TXFOUT and TXDOUT outputs.
All the monitoring levels and interrupt masks are user-
programmable. See Figure 1a.
Table 1. Acronyms
Figure 1a. ADC Channel Only for TXP when BURST_MODE = 1 in Table 02h, Register 89h
Figure 1b. ADC Channel
ACRONYM DESCRIPTION
ADC Analog-to-Digital Converter
APC Automatic Power Control
APD Avalanche Photodiode
DAC Digital-to-Analog Converter
LOS Loss of Signal
LUT LUT
NV Nonvolatile
QT Quick Trip
ROSA Receiver Optical Subassembly
SEE Shadowed EEPROM
ACRONYM DESCRIPTION
SFF Small Form Factor
SFF-8472
Document Defining Register Map of SFPs
and SFFs
SFP Small Form-Factor Pluggable
SFP+ Enhanced SFP
TE
Tracking Error. Deviation from linear of the
relationship between transmitted power and
monitor diode current.
TIA Transimpedance Amplifier
TOSA Transmit Optical Subassembly
TXP Transmit Power
1616
OFFSET
REGISTERS
16
16
RIGHT-SHIFT2
DETERMINED
BY KRMD
COMPARE
(MD0REGH[7:0] + 8
x MD1REGH[7:0])
65,536
TXP SCALE
TXFINT
SHIFT
ALARM AND WARNING
THRESHOLDS
RESULTS
REGISTERS
ALARM/
WARNING
FLAGS
ALARM/
WARNING
ENABLES
COUPLED*
SHIFT
RIGHT-SHIFT1
DETERMINED
BY KIMD
(A)
*USER HAS TO CALIBRATE THE GAIN USING THE SCALE REGISTERS
IN CASE RIGHT-SHIFTING IS DESIRED IN ORDER TO MAINTAIN CORRECT BIT WEIGHTING.
x
TXP =
ADC
13
OFFSET
REGISTERS
SCALE
REGISTERS
13 13
RIGHT-SHIFT
SETTINGS
COMPARE
ANALOG INPUT
TXFINT
SHIFT
ALARM AND WARNING
THRESHOLDS
ALARM/
WARNING
FLAGS
ALARM/
WARNING
ENABLES
COUPLED
*
*USER HAS TO CALIBRATE THE GAIN USING THE SCALE REGISTERS
IN CASE RIGHT-SHIFTING IS DESIRED IN ORDER TO MAINTAIN CORRECT BIT WEIGHTING.
(B)
13
RESULTS
REGISTERS