DS1884 datasheet(19/92 Pages) MAXIM

19 / 92 page

DS1884

SFP and PON ONU Controller

with Digital LDD Interface

Maxim Integrated

Detailed Description

The DS1884 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

DS1884 are shown in the Block Diagram and described

in subsequent sections.

Monitors and Fault Detection

Monitors

The DS1884 monitors five ADC channels. This monitoring

combined with the alarm enables (A2h Table 01h/05h)

determines when/if the DS1884 turns off the MAX3710

DACs and triggers the TXFOUT and TXDOUT outputs.

All the monitoring levels and interrupt masks are user-

programmable. See Figure 1.

ADC Monitors and Alarms

The ADC monitors temperature (internal temp sensor),

VCC, laser bias (TXB), laser power (TXP), and receive

power (RSSIC for coarse, RSSIF for fine) using an analog

multiplexer to measure them round-robin with a single

ADC (see the ADC Timing section). The voltage channels

have a customer-programmable full-scale range and all

channels have a customer-programmable offset value

that is factory programmed to a default value (Table 2).

Table 1. Acronyms

Table 2. ADC Default Monitor Full-Scale Ranges

Figure 1. 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

Nonvolatile

Quick Trip

ROSA

Receiver Optical Subassembly

SEE

Shadowed EEPROM

SFF

Small Form Factor

SFF-8472

Document Defining Register Map of SFPs

and SFFs

SFP

Small Form-Factor Pluggable

SFP+

Enhanced SFP

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

SIGNAL (UNITS)

+FS SIGNAL

+FS HEX

-FS SIGNAL

-FS HEX

Temperature (°C)

127.996

7FFFh

-128

8000h

VCC (V)

6.5528

FFF8h

0000h

TXB, TXP, RSSIC, RSSIF (V)

2.4997

FFF8h

0000h

ADC

OFFSET

REGISTERS

SCALE

REGISTERS

RIGHT-SHIFT

SETTINGS

COMPARE

ANALOG INPUT

*USER MUST CALIBRATE THE GAIN USING THE SCALE REGISTERS IN CASE RIGHT-SHIFTING IS DESIRED TO MAINTAIN CORRECT BIT WEIGHTING.

TXFINT

SHIFT

ALARM AND WARNING

THRESHOLDS

ALARM/

WARNING

FLAGS

ALARM/

WARNING

ENABLES

COUPLED*

DS1884 Datasheet(PDF) 19 Page - Maxim Integrated Products

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