SI3402-B Datasheet, PDF (1/21 Pages) Silicon Laboratories – FULLY-INTEGRATED 802.3-COMPLIANT POE PD INTERFACE AND LOW-EMI SWITCHING REGULATOR

Si3402-B
FULLY-INTEGRATED 802.3-COMPLIANT POE PD INTERFACE
AND LOW-EMI SWITCHING REGULATOR
Features
 Pin-compatible replacement for
the obsolete Si3402-A
 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
 Programmable classification
circuit
 Incorporates switcher EMI-
reduction techniques.
 Supports non-isolated and
isolated switching topologies
 Comprehensive protection
circuitry
Transient overvoltage
protection
Undervoltage lockout
Early power-loss indicator
Thermal shutdown protection
Foldback current limiting
 Low-profile 5 x 5 mm 20-pin QFN
 RoHS-compliant
Applications
 Voice over IP telephones and
adapters
 Wireless access points
 Security cameras
Description
 Point-of-sale terminals
 Internet appliances
 Network devices
 High power applications
The Si3402 integrates all power management and control functions required in a
Power-over-Ethernet (PoE) powered device (PD) application. The Si3402
converts the high voltage supplied over the 10/100/1000BASE-T Ethernet
connection into a regulated, low-voltage output supply. The optimized architecture
of the Si3402 minimizes the solution footprint, reduces external BOM cost, and
enables the use of low-cost external components while maintaining high
performance. The Si3402 integrates the required diode bridges and transient
surge suppressor, thus enabling direct connection of the IC 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 Si3402 supports IEEE 802.3at Type 1
Powered Device applications. Standard external resistors connected to the
Si3402 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 Si3402
is available in a low-profile, 20-pin, 5 x 5 mm QFN package. The Si3402 is
designed for IEEE 802.3at Type 1 (Class 3 and below) applications. The Si3402-B
is a pin-compatible replacement of the obsolete Si3402-A. PCB layouts designed
for Si3402-A can be reused with Si3402-B, but some component value changes
are required.
Ordering Information:
See page 18.
Pin Assignments
5 x 5 mm QFN
(Top View)
20 19 18 17 16 15
EROUT 1
SSFT* 2
VDD 3
ISOSSFT* 4
VNEG
(PAD)
14 CT1
13 CT2
12 VPOSF
11 SP1
5 6 7 8 9 10
Note:
Original pin names shown for compatibil-
ity reasons, but SSFT, ISOSSFT, VPOSS,
and VSS1 are not internally connected.
Rev. 1.0 11/15
Copyright © 2015 by Silicon Laboratories
Si3402-B