Si3406x Family Data Sheet
Fully-Integrated IEEE 802.3-Compliant POE+ PD Interface and
High-Efficiency Switching Regulators with Transistor Bypass,
Sleep, Wake, and LED Drive
The Si3406x family integrates all power management and control functions required in
a Power-over-Ethernet Plus (PoE+) powered device (PD) application. These devices
convert the high voltage supplied over the 10/100/1000BASE-T Ethernet connection to
a regulated, low-voltage output supply. The optimized architecture of this device family
minimizes the solution footprint and external BOM cost and enables the use of low-cost
external components while maintaining high performance. The Si3406x family integra-
tes 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, current mode controlled
switching regulator supports isolated or non-isolated flyback and buck converter topolo-
gies. The switching frequency for the regulator is tunable with a simple external resistor
value to help avoid unwanted harmonics for better emissions control. A synchronous
driver is provided to optionally drive a secondary side FET to improve efficiency of pow-
er conversion. Connection to the PSE switch is maintained during sleep by an optional
automated maintain-power-signature (MPS) signal.
These devices fully support the IEEE 802.3at specification for the cases of single or
two event classification. Standard external resistors provide the proper IEEE 802.3 sig-
natures for the detection function and programming of the classification mode, and in-
ternal startup circuits ensure well-controlled soft-start initial operation of both the hots-
wap switch and the voltage regulator.
The Si34061 and Si34062 add main transformer bias winding support for ultra-high-effi-
ciency operation.
The Si34061 includes support for external augmentation or full bypass of the internal
hotswap and/or switching FET for best power handling and thermal management at the
high end of Class 4, plus offers a further boost in power conversion efficiency when
needed.
The Si34062 includes support for sleep modes with wake function, as well as LED drive
capability. These features can be utilized to minimize standby current, control sleep
and wake states, and provide application status information using a solid or blinking
LED.
The Si3406 is available in a low-profile, 20-pin, 5 x 5 mm QFN package, and the
Si34061 and Si34062 are available in low-profile, 24-pin, 5 x 5 mm QFN packages.
KEY FEATURES
• Type 1 (PoE) or Type 2 (PoE+) power
• Full IEEE 802.3at compliance
• Synchronous secondary FET driver
• Current mode dc-dc converter
• Tunable switching frequency
• Auxiliary transformer winding support
• Auxiliary adapter support
• Internal hotswap and switching FET bypass
support
• Automated maintain-power-signature (MPS)
support
• Sleep mode augmented with wake pin,
mode control, and LED driver
• 120 V Absolute Max voltage performance
• Extended –40 to +85 °C temperature
• Compact ROHS-compliant 5 mm x 5 mm
QFN Package
APPLICATIONS
• Voice over IP telephones
• Wireless access points
• Security and surveillance IP cameras
• Lighting luminaires
• Point-of-sale terminals
• Internet appliances
• Network devices
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This information applies to a product under development. Its characteristics and specifications are subject to change without notice.
Preliminary Rev. 0.5
Si3406x Family Data Sheet
Ordering Guide
1. Ordering Guide
Table 1.1. Si3406x Ordering Guide
Ordering Part Number
Si3406-A-GM
Package
5 x 5 mm 20-QFN
Pb-free, RoHS-compliant
5 x 5 mm 24-QFN
Pb-free, RoHS-compliant
5 x 5 mm 24-QFN
Pb-free, RoHS-compliant
Temperature Range (Ambient)
–40 to 85 °C Extended
Applications
All Purposes
Any high-power, high-efficiency
uses, such as Wireless Access
Points and IP Cameras
IP Phones or other uses with
Sleep/Green mode
Si34061-A-GM
–40 to 85 °C Extended
Si34062-A-GM
–40 to 85 °C Extended
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Preliminary Rev. 0.5 | 2
Table of Contents
1. Ordering Guide
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Block Diagrams .
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. 4
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5
5
5
6
2.2 Power over Ethernet (PoE) Line-Side Interface .
2.2.1 Surge Protection . . . . . . . . .
2.2.2 Telephony Protection . . . . . . .
2.2.3 Detection and Classification . . . . .
2.3 Hotswap Switch .
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2.4 HSSW State Machine . . . . .
2.4.1 External HSSW FET Driver .
. 6
. 7
. 7
. 8
. 9
. 9
. 9
. 9
.10
.10
.10
.11
2.5 DC to DC Converter . . . . . . . . . . . . . . . . . . .
2.5.1 Average Current Sensing, Overcurrent, and Low-Current Detection .
2.5.2 Sync FET Driver . . . . . . . . . . . . . . . . . .
2.6 External HSSW FET Driver .
2.7 Tunable Oscillator
2.8 Regulators .
2.9 Sleep Mode
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2.10 Extended Sleep Mode.
2.11 External Wall Support .
3. Application Examples
. . . . . . . . . . . . . . . . . . . . . . . . . . . 12
. . . . . . . . . . . . . . . . . . . . . . . . . . 14
4. Electrical Specifications
5. Pin Descriptions
6. Packaging
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.21
5.1 Detailed Pin Descriptions .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
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.26
.28
.29
.31
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6.1 Package Outline: Si3406 .
6.2 Land Pattern: Si3406
6.3 Package Outline: Si34061/62.
6.4 Land Pattern: Si34061/62 .
7. Top Markings
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
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.32
.33
.34
7.1 Si3406 Top Marking .
7.2 Si34061 Top Marking .
7.3 Si34062 Top Marking .
8. Revision History
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
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Preliminary Rev. 0.5 | 3
Si3406x Family Data Sheet
System Overview
2. System Overview
The following Block Diagrams will give the designer a sense for the internal arrangement of functional blocks, plus their relationships to
external pins. The Block Diagrams are followed by a description of the features of these integrated circuits.
2.1 Block Diagrams
RDET
RFREQ
V11
VDD
VPOS
250kHz
OSCs
fixed: 250kHz
adjustable: 100...500kHz
11V
REGULATOR
I
BIAS
5V
REGULATOR
THERMAL
PROTECTION
VPOS-1.32V
CT1
FBH
FBL
EROUT
VSS+1.32V
CT2
SP1
DETECTION
250kHz
PoE
CONTROLLER
THERMAL
PROTECTION
HOT-SWAP
CONTROLLER
Start
CLASS
&
MPS
SP2
TVS
100V
CURRENT
MODE
PWM
CONTROLLER
DC/DC
SW
SWO
VSS
VNEG
HSSW
I
AVG
ISNS
HSO
V11
DRV
RCL
nT2P
nSLEEP
SYNCL
Figure 2.1. Si3406 Block Diagram
RDET
RFREQ
VT15
V11
VDD
VPOS
250kHz
OSCs
fixed: 250kHz
adjustable: 100...500kHz
AUX
WINDING
SUPPORT
I
BIAS
11V
REGULATOR
5V
REGULATOR
THERMAL
PROTECTION
CT1
VSS+1.32V
FBL
EROUT
CT2
SP1
DETECTION
250kHz
PoE
CONTROLLER
THERMAL
PROTECTION
HOT-SWAP
CONTROLLER
Start
CLASS
&
MPS
SP2
TVS
100V
CURRENT
MODE
PWM
CONTROLLER
DC/DC
SW
SWO
VSS
V11
DRV
EXTGD
VNEG
HSSW
I
PK
I
AVG
SWISNS
ISNS
HSO
V
EHSSW
DRV
V11
DRV
SYNCL
RCL
EXTHSW
ASUP
nT2P
nSLEEP
Figure 2.2. Si34061 Block Diagram
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Preliminary Rev. 0.5 | 4
Si3406x Family Data Sheet
System Overview
RDET
RFREQ
VT15
V11
VDD
VPOS
250kHz
OSCs
fixed: 250kHz
adjustable: 100...500kHz
AUX
WINDING
SUPPORT
I
BIAS
11V
REGULATOR
5V
REGULATOR
THERMAL
PROTECTION
VPOS-1.32V
CT1
FBH
FBL
EROUT
VSS+1.32V
CT2
SP1
DETECTION
250kHz
PoE
CONTROLLER
THERMAL
PROTECTION
HOT-SWAP
CONTROLLER
Start
CLASS
&
MPS
SP2
TVS
100V
CURRENT
MODE
PWM
CONTROLLER
DC/DC
SW
SWO
VSS
VNEG
HSSW
I
AVG
ISNS
HSO
V11
DRV
RCL
WAKE
MODE
LED
nT2P
nSLEEP
SYNCL
Figure 2.3. Si34062 Block Diagram
2.2 Power over Ethernet (PoE) Line-Side Interface
The PoE line interface consists of diode bridges, internal surge protection, and the protocol interface support for detection and classifi-
cation.
Internal diode bridge maximum current is given by the specification, I
RECT
. If the application needs to consume more current from the
power interface, an external diode bridge has to be used. The external bridge should be connected in parallel to the internal bridge and
the designer must ensure that the internal bridge will not conduct significant current by using low-voltage-drop external diodes.
The chip features active protection against surge transients and accidentally applied telephony voltages.
2.2.1 Surge Protection
The surge protection circuit is activated if the VPOS-VNEG voltage exceeds T
PROT
and
the hotswap switch is off (dc-dc is not pow-
ered). If the hotswap switch is on, the surge power is sunk in the dcdc’s capacitance.
The internal surge protection can be overridden with an external TVS if higher than specified surge conditions need be tolerated. The
external surge device must be connected in parallel to the internal one; therefore, the designer must ensure that the external surge
protection will activate prior to the internal surge protection.
2.2.2 Telephony Protection
The Si3406x provides protection against telephony ringing voltage. The telephony ringing is much longer than the surge pulse but it has
less energy, therefore, the Si3406x has a switch parallel with the supply (VPOS and VNEG). When the protection circuit is activated, it
turns ON the telephony switch; the ringing energy then dissipates on this switch and ringing generator resistance (> 400 Ω).
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Preliminary Rev. 0.5 | 5
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