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
Si3461
T
ABLE O F
C
ONTENTS
Section
Page
1. Typical Application Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Si3461 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2.1. Si3461-EVB Performance Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.2. PSE Timing Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
3. Typical Si3461-EVB Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4. Si3461-EVB Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1. Reset State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
4.2. Operating Mode Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5. Operating Mode Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1. Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2. Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.3. Power-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.4. Overload Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.5. Disconnect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.6. UVLO and OVLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.7. Status LED Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
6. Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
6.1. Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.2. External Component Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.3. Input DC Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
7. Si3461 Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
9. Package Outline: 11-Pin QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1. Solder Paste Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.2. PCB Landing Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
9.3. Marking Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Rev. 1.0
3
Si3461
1. Typical Application Schematic
V
IN
+50V
+50V
Optional 3.3V regulator
V
DD
+3.3V
VDD
+
Detect
&
Mark
CLSMARK
DC1
DC2
CLSMODE
DETA
VSENSE
ISENSE
STATUS
V
OUT
48 V
PSE
output
(to port
magnetics)
Si3461
RST
Classification
&
Gate drive
GND
GND
GND
DETECT
FAULT
PGOOD
-
Note: Refer to the Si3461-EVB User Guide for complete schematic details
Figure 1. Si3461 Typical Application Schematic
4
Rev. 1.0
Si3461
2. Si3461 Electrical Specifications
The following specifications apply to the Si3461 controller. Refer to Tables 4 and 5 and the Si3461-EVB User's
Guide and schematics for additional details about the electrical specifications of the Si3461-EVB reference design.
Table 1. Recommended Operating Conditions
Description
Operating Temperature Range
Thermal Impedance
VDD Input Supply Voltage
Symbol
T
A
JA
VDD
No airflow
During all operating modes
(detect, classification, disconnect)
Test Conditions
Min
–40
—
2.7
Typ
25
75
3.3
Max
+85
—
3.6
Unit
°C
°C/W
V
Table 2. Absolute Maximum Ratings*
Parameter
Ambient Temperature Under Bias
Storage Temperature
Voltage on RST or any I/O pin with respect to GND
Voltage on VDD with respect to GND
Maximum Total Current through VDD
and GND
Maximum Output Current into CLSMARK, DC1,
DC2, CLSMODE, STATUS, ISENSE, RST,
VSENSE, DETA (any I/O pin)
ESD Tolerance
Lead Temperature
Human Body Model
Soldering, 10 seconds maximum
VDD > 2.2 V
Conditions
Max Rating
–55 to +125
–65 to +150
–0.3 to 5.8
–0.3 to 4.2
500
Unit
°C
°C
V
V
mA
100
–2 kV to +2 kV
260
mA
V
°C
*Note:
Stresses above those listed in this table may cause permanent device damage. This is a stress rating only, and
functional operation of the devices at these or any conditions above those indicated in the operational listings of this
specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.
Rev. 1.0
5
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