Si3480
Si3480 P
OWER
M
ANAGEMENT
C
O N T R O L L E R
Features
Enables use of a smaller power
Pin programmable for overall
supply for a 4 or 8 port PoE
power supply capacity, port
system
power level, port priority, and
detection timing
Self-contained solution operates
LED indication of port status and
without the need for a host for
overall power consumption
unmanaged operation
No software required
20-pin Quad flat package
No data isolation required
(4x4 mm)
4x4 mm PCB footprint; RoHS
Fully compliant with IEEE 802.3
compliant
clause 33 for Power over Ethernet
including the 802.3at amendment
Extended operating temperature
range (–40 to +85 °C)
for higher power (30 W category 2
ports)
Description
N
ot
fo R
r N ec
om
ew
m
D e
es nd
ig e
ns d
SCL
20
SDA
1
2
3
4
5
GND
VDD
RST
NC
LED1
6
Ordering Information:
See Ordering Guide on page 9.
Pin Assignments
(Top View)
LEDBANK
PWRCFG
17
INT
POECFG
16
The Si3480 is a power manager intended for use with the Si3452 Power
over Ethernet (PoE) controller. The Si3480 enables the use of a smaller,
lower cost, and more efficiently-utilized power supply in an unmanaged
PoE Power Sourcing Equipment (PSE) system.
The Si3452 is capable of delivering over 30 W per port, which means that,
in a typical 8-port system, a 240 W power supply would have to be used
to avoid overload. Typically, not all ports are used at full power; so, a
smaller power supply in the range of 30 to 150 W can be used along with
the Si3480 power management controller.
The Si3480 power management controller is pin programmed. The pins
are used to set the power supply capacity, the number of low power
(category 1, 15.4 W), and high power (category 2, 30 W) ports, the port
priority, and the detection timing (Alternative A or Alternative B). The
Si3480 uses the real time overload and current monitoring capability of
the Si3452 to manage power for up to eight ports. Power management is
based on actual consumption rather than mere classification in order to
supply power to the greatest number of ports.
LED2
LED3
LED4
The Si3480 also provides LED drive to indicate port status and drive an
LED bar graph display to indicate the power supply capacity in use. If a
port is denied power due to power supply capacity limitations, the LED
indicators provide a simple and intuitive indication, helping a user
recognize and correct the overload situation by rebalancing loads or
adding mid-span power injectors to ports that would not otherwise be
powered. In case of a port overload, the port is easily re-enabled by
disconnecting the Powered Device (PD) and then reconnecting the PD
after correcting the overload situation.
Rev. 1.1 1/15
Copyright © 2015 by Silicon Laboratories
LED5
19
7
18
8
15
14
13
12
11
10
PRIOCFG
ALTCFG
LED8
LED7
LED6
9
Si3480
Si3480
T
ABLE
Section
OF
C
ONTENTS
Page
N
ot
fo R
r N ec
om
ew
m
D e
es nd
ig e
ns d
Rev. 1.1
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Typical Application Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
3. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3.1. Device Initialization and Configuration Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3.2. I
2
C Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3.3. LED Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
4. LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
4.1. Start-Up LED Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
4.2. Port Status LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
4.3. Power Meter LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
5. Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
6. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
7. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8. Landing Pattern: 20-Pin QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9. Top Marking: 20-Pin QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
3
Si3480
1. Electrical Specifications
Table 1. Recommended Operating Conditions
Description
Operating Temperature
Range
V
DD
Supply Voltage
LED Current
Symbol
T
A
V
DD
I
LED
Test Conditions
No airflow
All operating modes
LEDBANK pin at 50% duty cycle
Min
–40
2.7
—
Typ
—
—
20
Max
85
3.6
—
Units
°C
V
mA
Table 2. Absolute Maximum Ratings
Ambient Temperature under Bias
Storage Temperature
N
ot
fo R
r N ec
om
ew
m
D e
es nd
ig e
ns d
–55
—
–65
—
V
DD
> 2.2 V
–0.3
—
–0.3
—
—
—
—
—
Symbol
V
IH
V
IL
I
IL
Test Conditions
RST, SCL, SDA,
ALTCFG
RST, SCL, SDA,
ALTCFG
Min
2.0
—
Typ
—
—
RST, and all CFG pins
SCL and SDA high
I
OL
= 8.5 mA
I
OL
= 25 mA
I
OH
= –3 mA
I
OH
= –10 mA
Percent of V
DD
VDD = 3.0 V
VDD = 3.6 V
—
—
V
OL
V
OH
∆V
SENSE
I
DD
—
—
—
—
–1.5
—
—
—
1.0
—
V
DD
–0.8
—
—
—
Rev. 1.1
Parameter
Conditions
Min
Typ
Max
125
150
5.8
4.2
500
100
Units
°C
°C
V
V
mA
mA
Voltage on any I/O with respect to GND
Voltage on V
DD
with respect to GND
Maximum Total LED Current
Maximum LED Current per Pin
Note:
Stresses above those listed under absolute maximum ratings may cause permanent damage to the
device. This is a stress rating only, and functional operation of the devices at those or any other conditions
above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating
conditions for extended periods may affect device reliability.
Table 3. Electrical Characteristics*
Description
Input High
Input Low
Max
—
0.8
±1
0.6
—
V
DD
–0.7
—
+1.5
10
13
Units
V
V
µA
V
V
%
mA
Input Leakage Current
Output Low
(LED pins, SCL and SDA)
Output High
(LED Pins)
Sense Accuracy for Analog
Configuration Pins
V
DD
Current
*Note:
V
DD
= 2.7 to 3.6 V, –40 to 85 °C unless otherwise noted.
4
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
