SI3462 Datasheet, PDF (1/24 Pages) Silicon Laboratories – SINGLE-PORT IEEE 802.3AT POE/POE PSE INTERFACE

Si3462
SINGLE-PORT IEEE 802.3AT POE/POE+ PSE INTERFACE
Features
 IEEE 802.3at^TM compliant PSE
Short-circuit output fault
 Autonomous operation requires no
protection
host processor interface
LED status signal (detect,
 Complete reference design
power good, output fault)
available, including Si3462 controller ^{ UNH Interoperability Test Lab}
and schematic:
report available
Low-cost BOM
 Extended operating range
Compact PCB footprint
(–40 to +85 °C)
Operates directly from a +50 V ^{ 11-Pin Quad Flat No-Lead (QFN)}
isolated supply
package
Supports up to 30 W maximum
Tiny 3x3 mm PCB footprint;
output power (Class 4)
RoHS-compliant
Robust 3-point detection algorithm  No-classify modes force power
eliminates false detection events after valid detection
IEEE-compliant disconnect
Eliminates 10 BOM
Inrush current control
components
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 Si3462 is a single-port power management controller for IEEE 802.3at-
compliant Power Sourcing Equipment (PSE). The Si3462 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 Si3462'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 Si3462 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 Si3462 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
(Si3462-EVB), including a complete schematic and bill of materials. The
Si3462 also features “no-classify” modes, for circumstances where detection
is desired but classification steps can be skipped. Example applications
include dedicated, point-to-point connections for IP cameras, point-of-sale
terminals, and wireless access points where the application power
requirements are well understood. These modes allow elimination of
classification-related components from the bill of materials.
Pin Assignments
Si3462
CLSMARK ¹
DC1 ²
VDD 3
DC2 4
CLSMODE 5
GND
10 STATUS
9 ISENSE
8 _RST
7 VSENSE
6 DETA
11-pin QFN (3x3 mm)
Top View—Pads on bottom of package
Rev. 1.0 11/11
Copyright © 2011 by Silicon Laboratories
Si3462