Rev. 0.9 8/07 Copyright © 2007 by Silicon Laboratories Si3400/Si3401
This information applies to a product under development. Its characteristics and specifications are subject to change without notice.
Si3400
Si3401
FULLY-INTEGRATED 802.3-COMPLIANT PD INTERFACE
AND
SWITCHING REGULATOR
Features
Applications
Description
The Si3400 and Si3401 integrate all power management and control
functions required in a Power-over-Ethernet (PoE) powered device (PD)
application. The Si3400 and Si3401 convert the high voltage supplied over
the 10/100/1000BASE-T Ethernet connection into a regulated, low-voltage
output supply. The optimized architectures of the Si3400 and Si3401
minimize the solution footprint, reduce external BOM cost, and enable the
use of low-cost external components while maintaining high performance.
The Si3400 and Si3401 integrate the required diode bridges and transient
surge suppressors, thus enabling direct connection of ICs to the Ethernet
RJ-45 connector. The switching power FET and all associated functions are
also integrated. The integrated switching regulator supports isolated
(flyback) and non-isolated (buck) converter topologies. The Si3400 and
Si3401 support IEEE STD™ 802.3-2005 (future instances are referred to as
802.3) compliant solutions as well as pre-standard products, all in a single
IC. Standard external resistors connected to the Si3400 and Si3401 provide
the proper 802.3 signatures for the detection function and programming of
the classification mode. Startup circuits ensure well-controlled initial
operation of both the hotswap switch and the voltage regulator. The Si3400
and Si3401 are available in low-profile, 20-pin, 5 x 5 mm QFN packages.
While the Si3400 is designed for applications up to 10 W, the Si3401 is
optimized for higher power applications (up to approximately 15 W). See
also “AN313: Using the Si3400/01 in High Power Applications” for more
information.
IEEE 802.3 standard-compliant
solution, including pre-standard
(legacy) PoE support
Highly-integrated IC enables
compact solution footprints
Minimal external components
Integrated diode bridges and
transient surge suppressor
Integrated switching regulator
controller with on-chip power
FET
Integrated dual current-limited
hotswap switch
Support non-isolated and
isolated switching topologies
Comprehensive protection
circuitry
Transient overvoltage
protection
Undervoltage lockout
Early power-loss indicator
Thermal shutdown protection
Foldback current limiting
Programmable classification
circuit
Low-profile 5 x 5 mm 20-pin QFN
Pb-Free and RoHS-compliant
Voice over IP telephones and
adapters
Wireless access points
Security cameras
Point-of-sale terminals
Internet appliances
Network devices
High power applications (Si3401)
Notes:
1. Pin VSSA added on revisions CZ
and higher.
2. Pin ISOSSFT added on revisions
CZ and higher. Function available
on revision E silicon. For Rev CZ,
or to disable this feature on
Revision E, tie this pin to VDD.
Ordering Information:
See Ordering Guide on page
page 17.
Pin Assignments
5x5mm QFN
(Top View)
EROUT
SSFT
RDET
HSO
RCL
SP1
SP2
VPOSF
CT1
PLOSS
ISOSSFT
2
VDD
5678
9
10
151620 19 18 17
1
2
3
4
11
12
13
14
VNEG
VSSA
1
VPOSS
VSS1
SWO
VSS2
FB
VNEG
(PAD)
CT2
