ltc4264cde-trpbf Linear Technology Corporation, ltc4264cde-trpbf Datasheet

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ltc4264cde-trpbf

Manufacturer Part Number
ltc4264cde-trpbf
Description
High Power Pd Interface Controller With 750ma Current Limit
Manufacturer
Linear Technology Corporation
Datasheet
FEATURES
APPLICATIONS
TYPICAL APPLICATION
SPARE PAIR
–54V FROM
–54V FROM
DATA PAIR
Complete High Power PD Interface Controller
IEEE 802.3af
Onboard 750mA Power MOSFET
Complementary Power Good Outputs
Flexible Auxiliary Power Options
Precision Dual Current Limit with Disable
Programmable Classifi cation Current to 75mA
Onboard 25k Signature Resistor with Disable
Undervoltage Lockout
Complete Thermal Overload Protection
Available in Low Profi le (4mm × 3mm) DFN Package
802.11n Access Points
High Power VoIP Video Phones
RFID Reader Systems
PTZ Security Cameras and Surveillance Equipment
~
~
~
~
DF1501S
DF1501S
+
+
®
Compliant
0.1µF
SMAJ58A
R
CLASS
SHDN
R
I
V
LIM_EN
IN
CLASS
LTC4264
PWRGD
PWRGD
V
GND
OUT
MIN
5µF
+
RUN
SWITCHING
SUPPLY
POWER
RTN
DESCRIPTION
V
The LTC
terface controller intended for IEEE 802.3af Power over
Ethernet (PoE) and high power PoE applications up to 35W.
By including a precision dual current limit, the LTC4264
keeps inrush below the IEEE802.3af current limit levels
to ensure interoperability success while allowing for high
power PD operation. The LTC4264 includes a fi eld-proven
power MOSFET delivering up to 750mA to the PD load while
maintaining compliance with the IEEE802.3af standard.
Complementary power good outputs allow the LTC4264 to
interface directly with a host of DC/DC converter products.
The LTC4264 provides a complete signature and power
interface solution for PD designs by incorporating the 25k
signature resistor, classifi cation circuitry, input current
limit, undervoltage lockout, thermal overload protection,
signature disable and power good signaling.
The LTC4264 PD interface controller can be used along with
a variety of Linear Technology DC/DC converter products
to provide a complete, cost effective power solution for
high power PD applications.
The LTC4264 is available in the space-saving low profi le
(4mm × 3mm) DFN package.
All other trademarks are the property of their respective owners.
IN
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
4264 TA01a
High Power PD Interface
TO LOGIC
3.3V
®
+
4264 is an integrated Powered Device (PD) in-
Controller with 750mA
PWRGD – V
200mA/DIV
50V/DIV
50V/DIV
50V/DIV
V
OUT
OUT
V
I
IN
IN
Current Limit
Turn On vs Time
TIME (5ms/DIV)
LTC4264
C
LOAD
= 100µF
4264 TA01b
1
4264f

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ltc4264cde-trpbf Summary of contents

Page 1

... PD applications. The LTC4264 is available in the space-saving low profi le (4mm × 3mm) DFN package. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. LTC4264 V ...

Page 2

... V – 0. ORDER PART NUMBER LTC4264CDE LTC4264IDE Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. ...

Page 3

ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T SYMBOL PARAMETER V I Low Level Input Voltage IL_ILIM LIM_EN V Active Low Power Good PWRGD_OUT Output Low Voltage I Active Low Power Good Leakage PWRGD_LEAK V Active High Power ...

Page 4

LTC4264 TYPICAL PERFORMANCE CHARACTERISTICS Input Current vs Input Voltage 25k Detection Range 0 25°C A 0.4 0.3 0.2 0 –2 –4 –6 –8 INPUT VOLTAGE (V) 4264 G01 Signature Resistance vs Input Voltage 28 ∆V V2 ...

Page 5

PIN FUNCTIONS SHDN (Pin 1): Shutdown Input. Used to command the LTC4264 to present an invalid signature. Connecting SHDN to GND lowers the signature resistance to an invalid value and disables other LTC4264 operations. If unused, tie SHDN to V ...

Page 6

LTC4264 BLOCK DIAGRAM SHDN CLASS I 4 LIM_EN CLASSIFICATION CURRENT LOAD + 1.237V 16k – CONTROL CIRCUITS INPUT CURRENT LIMIT 1400mA + 750mA 300mA – BOLD LINE INDICATES ...

Page 7

APPLICATIONS INFORMATION OVERVIEW Power over Ethernet (PoE) continues to gain popularity as more products are taking advantage of having DC power and high speed data available from a single RJ45 connec- tor. As PoE is becoming established in the marketplace, ...

Page 8

LTC4264 APPLICATIONS INFORMATION PSE GND 0.1µF 0.1µF DGND BYP AGND 3.3V V DETECT DD AUTO CMPD3003 1k 1/4 LTC4259A 0.47µF V SENSE GATE OUT EE 10k S1B 0.25Ω –54V IRLR3410 GND 0.1µF AGND DETECT CMPD3003 1k 1/4 LTC4259A 0.47µF V ...

Page 9

APPLICATIONS INFORMATION DETECTION V1 DETECTION V2 CLASSIFICATION –10 –20 UVLO –30 TURN-ON –40 –50 –10 UVLO UVLO –20 OFF ON –30 – LIMIT_LOW = dt C1 –50 –10 POWER POWER –20 BAD GOOD –30 –40 –50 20 POWER ...

Page 10

LTC4264 APPLICATIONS INFORMATION RJ45 POWERED 6 DEVICE (PD) INTERFACE AS DEFINED 4 BY IEEE 802.3af Figure 4. PD Front End Using Diode Bridges on Main and Spare Inputs pin high will reduce the signature ...

Page 11

APPLICATIONS INFORMATION During classifi cation, the PSE presents a fi xed voltage between –15.5V and –20.5V to the PD (Figure 6). With the input voltage in this range, the LTC4264 asserts a load current from the GND pin through the ...

Page 12

LTC4264 APPLICATIONS INFORMATION UNDERVOLTAGE LOCKOUT The IEEE 802.3af specifi cation dictates a maximum turn- on voltage of 42V and a minimum turn-off voltage of 30V for the PD. In addition, the PD must maintain large on-off hysteresis to prevent current-resistance ...

Page 13

APPLICATIONS INFORMATION During the inrush event being charged, a large amount of power is dissipated in the MOSFET. The LTC4264 is designed to accept this load and is thermally protected to avoid damage to the onboard power ...

Page 14

LTC4264 APPLICATIONS INFORMATION The active high PWRGD pin features an internal, open- collector output referenced to V OUT active high PWRGD pin pulls low until the load capacitor is fully charged. At that point, PWRGD becomes high impedance, indicating the ...

Page 15

APPLICATIONS INFORMATION thermal shutdown. For DC loads the maximum ambient temperature can be calculated as: = 125 – θ T • PWR (°C) MAX JA where T is the maximum ambient operating tempera- MAX ture, θ is the junction-to-ambient thermal ...

Page 16

LTC4264 APPLICATIONS INFORMATION Diode Bridge IEEE 802.3af allows power wiring in either of two confi gu- rations on the TX/RX wires, and power can be applied to the PD via the spare wire pair in the RJ45 connector. The PD ...

Page 17

APPLICATIONS INFORMATION OPTION 1: AUXILIARY POWER INSERTED BEFORE LTC4264 RJ45 + – PHY RX 3 – SPARE – SPARE 8 + ISOLATED WALL V WW TRANSFORMER – ...

Page 18

LTC4264 APPLICATIONS INFORMATION will be drawn from the PSE. On the other hand, if the adapter voltage is lower, the PSE will continue to supply power to the PD and the adapter will not be used. Proper operation will occur ...

Page 19

APPLICATIONS INFORMATION R from Table unique load current is required, CLASS the value of R can be calculated as: CLASS R = 1.237V/(I – I CLASS LOAD IN_CLASS I is the LTC4264 IC supply current during clas- ...

Page 20

LTC4264 APPLICATIONS INFORMATION Shutdown Interface To disable the 25k signature resistor, connect SHDN to the GND pin. Alternately, the SHDN pin can be driven high with respect Examples of interface circuits IN that disable the signature and ...

Page 21

APPLICATIONS INFORMATION avoid the possibility of leakage shutting down the OUT LTC4264. If not used, tie SHDN to V The load capacitor connected between GND and V of the LTC4264 can store signifi cant energy when fully ...

Page 22

LTC4264 APPLICATIONS INFORMATION 22 4264f ...

Page 23

... ON THE TOP AND BOTTOM OF PACKAGE Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. DE Package 12-Lead Plastic DFN (4mm × ...

Page 24

... Single IEEE 802.3af Power over Ethernet Controller LTC4263-1 High Power Single PSE Controller LTC4267 IEEE 802.3af PD Interface with an Integrated Switching Regulator Burst Mode is a registered trademark of Linear Technology Corporation Linear Technology Corporation 24 1630 McCarthy Blvd., Milpitas, CA 95035-7417 ● (408) 432-1900 ...

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