SI3460 Datasheet, PDF (1/22 Pages) Silicon Laboratories – IEEE 802.3af PSE INTERFACE AND DC-DC CONTROLLER

Si3460
IEEE 802.3af PSE INTERFACE AND DC-DC CONTROLLER
Features
IEEE 802.3af™ compliant PSE and
dc-dc controller
Autonomous operation requires no
host processor interface
Complete reference design
available, including Si3460 controller,
PSE firmware, and schematic:
Low-cost BOM with compact PCB
footprint
Operates directly from a +12 or
+15 V isolated supply
dc-dc controller generates –48 V
PSE output for SELV compatibility
with telephony interfaces
Supports up to 15.4 W maximum
output power (Class 0)
Applications
Robust 3-point detection
algorithm eliminates false
detection events
IEEE-compliant classification
IEEE-compliant disconnect
Inrush current control
Short-circuit output fault
protection
LED status signal (detect,
power good, output fault)
UNH Interoperability Test Lab test
report available
Extended operating range
(–40 to +85 °C)
11-Pin Quad Flat No-Lead (QFN)
Tiny 3 x 3 mm PCB footprint;
Pb-free, RoHS-compliant
Pin Assignments
Si3460
GATE ¹
CTRL1 ²
VDD 3
CTRL2 4
250KHZ 5
GND
10 STATUS
9 ISENSE
8 _RST
7 VSENSE
6 DETA
11-pin QFN (3x3 mm)
Top View—Pads on bottom of package
IEEE 802.3af endpoints and
midspans
Environment A and B PSEs
Embedded PSEs
Set-top boxes
FTTH media converters
Cable modem and DSL
gateways
Description
The Si3460 is a single-port –48 V power management controller for
IEEE 802.3af-compliant Power Sourcing Equipment (PSE). Designed
to minimize system cost and ease of implementation in embedded
PSE endpoint (switches) or midspan (power injector) applications, the
Si3460 operates directly from a 12 or 15 V input supply and integrates
a digital PWM-based dc-dc converter for generating the –48 V PSE
output supply. The IEEE-required Powered Device (PD) detection
feature uses a robust 3-point algorithm to avoid false detection events.
The Si3460's reference design kit also provides full IEEE-compliant
classification and PD disconnect. Intelligent protection circuitry
includes input undervoltage lockout (UVLO), current limiting, and
output short circuit protection. The Si3460 is designed to operate
completely independently of host processor control. An LED status
signal is provided to indicate the port status, including detect, power
good, and output fault event information for use within the host
system. The Si3460 is pin-programmable to support endpoint and
midspan applications, as well as each of the different classification
power levels specified by the IEEE 802.3af standard. A
comprehensive reference design kit is available (Si3460-EVB),
including a complete schematic and BOM (Bill-of-Materials) for the dc-
dc converter and PSE functions.
Preliminary Rev. 0.4 11/07
Copyright © 2007 by Silicon Laboratories
Si3460
This information applies to a product under development. Its characteristics and specifications are subject to change without notice.