FEATURES
nn Four PSE Ports
nn Two Power Channels Per Port
nn Fully Compliant IEEE 802.3bt Type 3 and 4 PSE
nn Compliant Support for Type 1, 2, 3, and 4 PDs
nn Low Power Path Dissipation per Channel
nn 150mΩ Sense Resistance
nn 30mΩ or Lower MOSFET RDS(ON)
nn Chipset Provides Electrical Isolation
nn Eliminates Optos and Isolated 3.3V Supply
nn Very High Reliability Multipoint PD Detection
nn Connection Check Distinguishes Single-
Signature and Dual-Signature PDs
nn Continuous, Dedicated Per-Port Power and Current
Monitoring
nn Per-Port Power Policing
nn 1MHz I2C Compatible Serial Control Interface
nn Pin or I2C Programmable PD Power Up to 71.3W
nn Available in a 40-Lead 6mm × 6mm (LTC4292) and
24-Lead 4mm × 4mm (LTC4291) QFN Package
APPLICATIONS
nn PoE PSE Switches/Routers
nn PoE PSE Midspans
LTC4292/LTC4291
4-Port IEEE 802.3bt
PoE PSE Controller
DESCRIPTION
The LTC®4292/LTC4291 chipset is a 4-port power sourc-
ing equipment (PSE) controller designed for use in IEEE
802.3bt Type 3 and 4 compliant Power over Ethernet
(PoE) systems. The LTC4292/LTC4291 is designed to
power compliant 802.3af, 802.3at, and 802.3bt PDs.
The LTC4292/LTC4291 chipset delivers lowest-in-indus-
try heat dissipation by utilizing low-RDS(ON) external
MOSFETs and 0.15Ω sense resistance per power channel.
A transformer-isolated communication protocol replaces
expensive opto-couplers and complex isolated 3.3V sup-
ply, resulting in significant BOM cost savings.
Advanced power management features include per-
port 14‑bit current monitoring, programmable current
limit, and versatile fast shut-down of preselected ports.
Advanced power management host software is available
under a no-cost license. PD detection uses a proprietary
multipoint detection mechanism ensuring excellent immu-
nity from false PD identification. Autoclass and 5-event
physical classification are supported. The LTC4292/
LTC4291 includes an I2C serial interface operable up to
1MHz. The LTC4292/LTC4291 is pin or I2C programmable
to negotiate PD delivered power up to 71.3W.
All registered trademarks and trademarks are the property of their respective owners.
TYPICAL APPLICATION
(NO I2C
ISOLATION
REQUIRED)
0.1µF 3.3V
GP0 VDD
GP1
4PVALID
AUTO
RESET
MSD
INT LTC4291
SCL
SDAIN
SDAOUT
AD0
AD1
AD2
AD3 DGND
10Ω AGNDP
>47µF
1µF
100V
VEE
ISOLATION
PWRMD0
PWRMD1
AGNDP
OUTnA
CPD
3.3V
CND
DPD
3.3V
DND
100Ω
100Ω
100Ω
100Ω
1µF
CAP1
2nF
2kV
CPA
100Ω
VEE
100Ω
CNA
DPA
100Ω
VEE
100Ω
DNA
GATEnA
SENSEnA
LTC4292
OUTnB
GATEnB
0.1µF
CAP2
VEE
SENSEnB
VSSKn
VEE
AGNDP
0.22µF
100V
S1B
TX1
0.15Ω
AGNDP
0.22µF
100V
S1B
VEE
VSSKn
TX2
TX3
S1B
0.15Ω
0.22μF, 100V
S1B TX4
VSSKn VEE
1000BASE-T
(1 OF 4 PORTS)
0.15Ω AGNDP
VSSKn
1
2
3
6
4
5
7
8
RJ45
429291 TA01a
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