DS1877T+ Maxim Integrated Products, DS1877T+ Datasheet - Page 13

• Manufacturer Part Number: DS1877T+
• Description: IC CTLR/MON SFP 1-2CH 28TQFN
• Manufacturer: Maxim Integrated Products
• Type: SFP+ Controllerr

Specifications of DS1877T+

• Input Type: Logic
• Output Type: Logic
• Interface: I²C
• Current - Supply: 2.5mA
• Mounting Type: Surface Mount
• Package / Case: 28-WFQFN exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 90-1877T+000

Figure 1. Power-Up Timing
Figure 2. Quick-Trip Sample Timing
The DS1877 integrates the control and monitoring func-
tionality required in an SFP or SFP+ system. The device
is specifically designed for a dual-receiver SFP module.
Key components of the device are shown in the Block
Diagram and described in subsequent sections.
On power-up, the device sets the DACs to high imped-
ance. After time t
dition set in EEPROM. After a temperature conversion is
completed and if the VCC LO alarm is enabled, an addi-
tional V
LO alarm level is required before the DACs are updated
with the value determined by the temperature conversion
and the DAC LUT. See Figure 1.
As shown in Figure 2, the device’s input comparator is
shared between two LOS comparisons. The comparator
polls the alarms in a multiplexed sequence. The com-
parator checks the LOS (RSSI1_ and RSSI2_) signals
against the internal reference. Depending on the results
of the comparison, the corresponding alarms and warn-
ings are asserted or deasserted. Any QT alarm that is
detected by default remains active until a subsequent
comparator sample shows that the condition no longer
exists.
CC
SETTINGS
conversion above the customer-defined VCC
DAC
V
CC
INIT
, the DACs are set to an initial con-
Detailed Description
V
POA
DACs During Power-Up
SFP Controller for Dual Rx Interface
HIGH IMPEDANCE
QUICK-TRIP SAMPLE TIMES
Quick-Trip Timing
500µs
LOS2
OFF STATE
t
INIT
Table 1. Acronyms
ACRONYM
LOS1
t
SFF-8472
REP
ROSA
SFP+
AGC
ADC
APC
APD
DAC
ATB
LOS
LUT
SEE
SFF
SFP
TIA
NV
QT
LOS2
LUT VALUE
Analog-to-Digital Converter
Automatic Gain Control
Automatic Power Control
Avalanche Photodiode
Alarm Trap Bytes
Digital-to-Analog Converter
Loss of Signal
Lookup Table
Nonvolatile
Quick Trip
Transimpedance Amplifier
Receiver Optical Subassembly
Shadowed EEPROM
Small Form Factor
Document Defining Register Map of SFPs
and SFFs
Small Form Factor Pluggable
Enhanced SFP
LOS1
DESCRIPTION
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