LTC4259A-1_15 Datasheet, PDF (1/32 Pages) Linear Technology – Quad IEEE 802.3af Power over Ethernet Controller with AC Disconnect

LTC4259A-1
Quad IEEE 802.3af
Power over Ethernet Controller
with AC Disconnect
FEATURES
DESCRIPTIO
■ _{Controls Four Independent – 48V Powered}
Ethernet Ports
■ _{Each LTC4259A-1 Port Includes:}
– IEEE 802^®.3af Compliant PD Detection and
Classification
– Output Current Limit with Foldback
– Short-Circuit Protection with Fast Gate Pull-Down
– PD Disconnect Using AC or DC Sensing
– Improved AC Disconnect
– Improved UVLO
■ _{Operates Autonomously or Controlled by I}²_C^TM
Serial Interface
■ _{4-Bit Programmable Digital Address Allows Control}
of Up to 64 Ports
■ _{Current and Duty Cycle Limits Protect External FETs}
■ _{IMPROVED UVLO}
■ _{Available in a 36-pin SSOP package.}
U
APPLICATIO S
■ _{IEEE 802.3af Compliant Endpoint and Midspan}
Power Sources
■ _{IP Phone Systems}
■ _{DTE Power Distribution}
The LTC^®4259A-1 is a quad –48V Hot Swap^TM controller
designed for use in IEEE 802.3af compliant Power Sourc-
ing Equipment (PSE). It consists of four independent ports,
each with output current limit, short-circuit protection, com-
plete Powered Device (PD) detection and classification ca-
pability, and programmable PD disconnect using AC or DC
sensing. Used with power MOSFETs and passives as in
Figure 1, the LTC4259A-1 can implement a complete IEEE
802.3af-compliant PSE.
The LTC4259A-1 can operate autonomously or be controlled
by an I²C serial interface. Up to 16 LTC4259A-1s may co-
exist on the same data bus, allowing up to 64 powered
Ethernet ports to be controlled with only two digital lines. Fault
conditions are optionally signaled with a programmable INT
pin to eliminate software polling.
External power MOSFETs, current sense resistors and di-
odes allow easy scaling of current and power dissipation
levels and provide protection against voltage and current
spikes and ESD events.
Linear Technology also provides solutions for 802.3af PD
applications with the LTC4257, LTC4257-1 and LTC4267.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Hot Swap is a registered trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
3.3V
0.1µF
0.1µF
100V X7R
–48V
SCL INT
SDAIN
SDAOUT
AD0
AD1
AD2
AD3
SHDN1 SHDN2 SHDN3 SHDN4
V_DD
OSCIN AUTO BYP
LTC4259A-1
RESET
DETECT1
DETECT2
DETECT3
DETECT4
DGND AGND V_EE SENSE1 GATE1 OUT1 SENSE2 GATE2 OUT2 SENSE3 GATE3 OUT3 SENSE4 GATE4 OUT4
R_S1
10k
10k
10k
10k
CMPD3003
×4
1k
×4
0.47µF
100V ×4
X7R
0.1µF
Q1
R_S2
Q2
R_S3
Q3
R_S4
RS1 TO RS4: 0.5Ω
Q1 TO Q4: IRFM120A
Q4
S1B ×4
Figure 1. Complete 4-Port Powered Ethernet Power Source
0.1µF 100V SMAJ58A
×4
×4
PORT1
PORT2
PORT3
PORT4
4259A F01
4259a1fa
1