Si3461
S
INGLE
-P
ORT
IEEE 802.3
AT
P
O
E/P
O
E+ PSE I
NTERFACE
Features
IEEE-compliant disconnect
IEEE 802.3at
TM
compliant PSE
Inrush current control
Autonomous operation requires
Short-circuit output fault
no host processor interface
protection
Complete reference design
LED status signal (detect,
power good, output fault)
available, including Si3461
controller and schematic:
UNH Interoperability Test Lab
report available
Low-cost BOM
Compact PCB footprint
Extended operating range
Operates directly from a +50 V
(–40 to +85 °C)
isolated supply
11-Pin Quad Flat No-Lead
Supports up to 30 W maximum
(QFN) package
output power (Class 4)
Pin Assignments
Si3461
11
CLSMARK
DC1
VDD
DC2
CLSMODE
1
2
3
4
5
11
11
11
10
9
STATUS
ISENSE
RST
VSENSE
DETA
GND
8
7
6
Robust
3-point detection algorithm
eliminates false detection events
Tiny
3x3 mm PCB footprint;
RoHS-compliant
11-pin QFN (3x3 mm)
Top View—Pads on bottom of package
Applications
IEEE 802.3at endpoints and
midspans
Environment A and B PSEs
Embedded PSEs
Set-top boxes
FTTH media converters
Cable modem and DSL
gateways
Description
The Si3461 is a single-port power management controller for IEEE
802.3at-compliant Power Sourcing Equipment (PSE). The Si3461 can
be powered from a 50 V input using a shunt regulator, or, to save
power, it can be powered from 50 V and 3.3 V power supplies. The
IEEE-required Powered Device (PD) detection feature uses a robust
3-point algorithm to avoid false detection events. The Si3461's
reference design kit also provides full IEEE-compliant classification
and PD disconnect. Intelligent protection circuitry includes input under-
voltage lockout (UVLO), classification-based current limiting, and
output short-circuit protection. The Si3461 is designed to operate
completely independently of host processor control. An LED status
signal is provided to indicate the port status, including detection,
power good, and output fault event information. The Si3461 is pin-
programmable to support four available power levels, endpoint and
mid-span applications, and auto-retry or restart after disconnect
functions. A comprehensive reference design kit is available (Si3461-
EVB), including a complete schematic and bill of materials.
Rev. 1.0 5/10
Copyright © 2010 by Silicon Laboratories
Si3461
SILABS [ SILICON LABORATORIES ]
