IC PD/OPTO FLYBACK CTRLR 32-DFN

LTC4269IDKD-1#TRPBF

Manufacturer Part NumberLTC4269IDKD-1#TRPBF
DescriptionIC PD/OPTO FLYBACK CTRLR 32-DFN
ManufacturerLinear Technology
TypePower Over Ethernet (PoE)
LTC4269IDKD-1#TRPBF datasheet
 


Specifications of LTC4269IDKD-1#TRPBF

ApplicationsPower Interface Switch for Power Over Ethernet (PoE) DevicesVoltage - Supply14 V ~ 16 V
Operating Temperature-40°C ~ 85°CMounting TypeSurface Mount
Package / Case32-DFNCurrent - Supply1.35mA
InterfaceIEEE 802.3afController TypePowered Device Interface Controller (PD)
Lead Free Status / RoHS StatusLead free / RoHS Compliant  
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FEATURES
n
25.5W IEEE 802.3at Compliant (Type 2) PD
n
Integrated State-of-the-Art Synchronous Flyback
Controller
– Isolated Power Supply Effi ciency >92%
– 88% Effi ciency Including Diode Bridge and
Hot Swap™ FET
n
Flexible Integrated Auxiliary Power Support
n
Superior EMI Performance
n
Robust 100V 0.7Ω (Typ) Integrated Hot Swap MOSFET
n
IEEE 802.3at High Power Available Indicator
n
Integrated Signature Resistor and Programmable
Class Current
n
Undervoltage, Overvoltage and Thermal Protection
n
Short-Circuit Protection with Auto-Restart
n
Programmable Soft-Start and Switching Frequency
n
Complementary Power Good Indicators
Thermally Enhanced 7mm × 4mm DFN Package
n
APPLICATIONS
n
VoIP Phones with Advanced Display Options
n
Dual-Radio Wireless Access Points
n
PTZ Security Cameras
n
RFID Readers
n
Industrial Controls
TYPICAL APPLICATION
~
+
54V FROM
DATA PAIR
~
~
+
54V FROM
SPARE PAIR
~
30.9Ω
0.1μF
Synchronous No-Opto
DESCRIPTION
The LTC
®
4269-1 is an integrated Powered Device (PD)
controller and switching regulator intended for high
power IEEE 802.3at and 802.3af applications. The
LTC4269-1 is targeted for high effi ciency, single and
multioutput applications from 10W to 25W. By support-
ing both 1-event and 2-event classifi cations, as defi ned
by the IEEE, the LTC4269-1 can be used in a wide range
of product confi gurations.
The LTC4269-1 synchronous, current mode, fl yback con-
troller generates multiple supply rails in a single conversion
step providing for the highest system effi ciency while main-
taining tight regulation across all outputs. The LTC4269-1
includes Linear Technology’s patented No-Opto feedback
topology to provide full IEEE 802.3 isolation without the
need of an opto-isolator circuit. A true soft-start function
allows graceful ramp-up of all output voltages.
All Linear Technology PD solutions include a shutdown
pin to provide fl exible auxiliary power options. The
LTC4269-1 can accommodate adaptor voltages from 18V
to 60V and supports both PoE or aux dominance options.
The LTC4269-1 is available in a space saving 32-pin DFN
package.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. Hot Swap is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents, including
5841643.
25W High Effi ciency PD Solution
10μH
V
IN
+
2.2μF
39k
10μF
383k
27.4k
10μF
TO MICRO
14k
3.01k
CONTROLLER
T2P
FB
V
PG
SENSE
PWRGD
UVLO
CC
V
PORTP
R
CLASS
SENSE
LTC4269-1
SHDN
SG
V
V
PORTN
CMP
V
SYNC
GND
OSC
PGDLY
t
ENDLY
R
C
NEG
ON
CMP
CMP
12k
100k
38.3k
1.21k
33pF
LTC4269-1
IEEE 802.3at PD with
Flyback Controller
0.18μH
5V
5A
+
47μF
100μF
+
33mΩ
2.2nF
1μF
10nF
0.1μF
42691 TA01a
42691fb
1

LTC4269IDKD-1#TRPBF Summary of contents

  • Page 1

    ... The LTC4269-1 is available in a space saving 32-pin DFN package. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5841643. 25W High Effi ...

  • Page 2

    ... LTC4269CDKD-1#PBF LTC4269CDKD-1#TRPBF LTC4269IDKD-1#PBF LTC4269IDKD-1#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. For more information on lead free part marking, go to: For more information on tape and reel specifi cations, go to: ...

  • Page 3

    ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T PARAMETER Interface Controller (Note 4) Operating Input Voltage Signature Range Classifi cation Range ON Voltage OFF Voltage Overvoltage Lockout ON/OFF Hysteresis Window Signature/Class Hysteresis Window Reset Threshold Supply Current Supply ...

  • Page 4

    LTC4269-1 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T PARAMETER PWM Controller (Note 10) Power Supply V Turn-On Voltage CC(ON) V Turn-Off Voltage CC(OFF) V Hysteresis CC V Shunt Clamp CC V Supply Current ...

  • Page 5

    ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T PARAMETER Load Compensation Load Compensation to V Offset Voltage SENSE Feedback Pin Load Compensation Current UVLO Function UVLO Pin Threshold (V ) UVLO UVLO Pin Bias Current Note 1: Stresses ...

  • Page 6

    LTC4269-1 TYPICAL PERFORMANCE CHARACTERISTICS Input Current vs Input Voltage 25k Detection Range 0 25°C A 0.4 0.3 0.2 0 VOLTAGE (V) PORTP 42691 G01 Signature Resistance vs Input Voltage 28 V ...

  • Page 7

    TYPICAL PERFORMANCE CHARACTERISTICS V and V CC(ON) CC(OFF) vs Temperature CC(ON CC(OFF –50 – 100 TEMPERATURE (°C) 42691 G10 SENSE Voltage vs Temperature 110 FB ...

  • Page 8

    LTC4269-1 TYPICAL PERFORMANCE CHARACTERISTICS Feedback Amplifi er Output Current 125°C 25°C 50 –40° –10 –30 –50 –70 0.9 1 1.1 1.2 1.3 1.4 V (V) FB 42691 G19 Feedback Amplifi er Voltage Gain vs ...

  • Page 9

    TYPICAL PERFORMANCE CHARACTERISTICS Minimum PG On-Time vs Temperature 340 R = 158k tON(MIN) 330 320 310 300 290 280 270 260 –50 – 100 TEMPERATURE (°C) 42691 G28 PIN FUNCTIONS SHDN (Pin 1): Shutdown Input. Use ...

  • Page 10

    LTC4269-1 PIN FUNCTIONS the V voltage and thus limits peak current until soft- CMP start is complete. The ramp time is approximately 70ms per μF of capacitance. Leave SFST open if not using the soft-start function. OSC (Pin 15): Oscillator. ...

  • Page 11

    BLOCK DIAGRAM SHDN 1 T2P 2 R CLASS PORTN 5 V PORTN UVLO CC + – 1.237V 15.3V REFERENCE (V UVLO 18 OSC 15 OSCILLATOR SYNC 13 ...

  • Page 12

    LTC4269-1 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 connector. As PoE continues to grow in the marketplace, ...

  • Page 13

    APPLICATIONS INFORMATION Table 1. LTC4269-1 Modes of Operation as a Function of Input Voltage V –V (V) LTC4269-1 MODES OF OPERATION PORTP PORTN 0V to 1.4V Inactive (Reset After 1st Classifi cation Event) 1.5V to 9.8V 25k Signature Resistor Detection ...

  • Page 14

    LTC4269-1 APPLICATIONS INFORMATION SIGNATURE CORRUPT OPTION In some designs that include an auxiliary power option necessary to prevent a PD from being detected by a PSE. The LTC4269-1 signature resistance can be corrupted with the SHDN pin (Figure ...

  • Page 15

    APPLICATIONS INFORMATION 50 40 1st CLASS 30 2nd CLASS DETECTION V1 1st MARK 2nd MARK DETECTION V2 INRUSH 1st CLASS 2nd CLASS 40mA DETECTION V1 1st MARK 2nd MARK DETECTION INRUSH = dt C1 ...

  • Page 16

    LTC4269-1 APPLICATIONS INFORMATION To control the power-on surge currents in the system, the LTC4269-1 provides a fi xed inrush current, allowing C1 to ramp up to the line voltage in a controlled manner. The LTC4269-1 keeps the PD inrush current ...

  • Page 17

    APPLICATIONS INFORMATION from commencing operation before the PD interface completely charges the reservoir capacitor, C1. The active low PWRGD pin connects to an internal, open- drain MOSFET referenced to V PORTN indicator bit when power good is declared and active. ...

  • Page 18

    LTC4269-1 APPLICATIONS INFORMATION Input Diode Bridge Figure 2 shows how two diode bridges are typically con- nected application. One bridge is dedicated to the data pair while the other bridge is dedicated to the spare pair. The ...

  • Page 19

    APPLICATIONS INFORMATION Transient Voltage Suppressor The LTC4269-1 specifi absolute maximum voltage of 100V and is designed to tolerate brief overvoltage events. However, the pins that interface to the outside world can routinely see excessive peak voltages. To protect ...

  • Page 20

    ... PoE to auxiliary power when auxiliary power is applied, however, the removal of auxiliary power to PoE power is not seamless unused, connect Contact Linear Technology applications support for detail information on implementing a custom auxiliary power supply. IEEE 802.3at SYSTEM POWER-UP REQUIREMENT Under the IEEE 802.3at standard must operate ...

  • Page 21

    APPLICATIONS INFORMATION SWITCHING REGULATOR OVERVIEW The LTC4269-1 includes a current mode converter designed specifi cally for use in an isolated fl yback topology employing synchronous rectifi cation. The LTC4269-1 operation is similar to traditional current mode switchers. The major difference ...

  • Page 22

    LTC4269-1 APPLICATIONS INFORMATION LTC4269-1 FEEDBACK AMP 1.237V – + COLLAPSE DETECT ENABLE Figure 10a. LTC4269-1 Switching Regulator Feedback Amplifi er PRIMARY-SIDE MOSFET DRAIN VOLTAGE VOLTAGE SG VOLTAGE Figure 10b. LTC4269-1 Switching Regulator ...

  • Page 23

    APPLICATIONS INFORMATION Enable Delay Time (ENDLY) The fl yback pulse appears when the primary-side switch shuts off. However, it takes a fi nite time until the transformer primary-side voltage waveform represents the output voltage. This is partly due to rise ...

  • Page 24

    LTC4269-1 APPLICATIONS INFORMATION in sensed output voltage, compensating for the IR drops. Assuming relatively fi xed power supply effi ciency, Eff, power balance gives Eff • P OUT IN V • Eff • V • I ...

  • Page 25

    APPLICATIONS INFORMATION Note the use of the external feedback resistive divider ratio to set output voltage provides the user additional freedom in selecting a suitable transformer turns ratio. Turns ratios that are the simple ratios of small integers; e.g., 1:1, ...

  • Page 26

    LTC4269-1 APPLICATIONS INFORMATION A fi nal note—the susceptibility of the system to bistable behavior is somewhat a function of the load current/ voltage characteristics. A load with resistive—i.e V/R behavior—is the most apt to be bistable. Capacitive loads ...

  • Page 27

    APPLICATIONS INFORMATION in an abrupt increase in inductor ripple current and, consequently, output voltage ripple. Do not allow the core to saturate! The maximum peak primary current occurs at minimum ⎛ MIN = I ...

  • Page 28

    LTC4269-1 APPLICATIONS INFORMATION Selecting the Load Compensation Resistor The expression for R was derived in the Operation CMP section as • 1− DC SENSE = K1• R • R1• N CMP ESR + R DS(ON) Continuing the ...

  • Page 29

    APPLICATIONS INFORMATION trace length and area to minimize stray capacitance and potential noise pick-up. You can synchronize the oscillator frequency to an external frequency. This is done with a signal on the SYNC pin. Set the LTC4269-1 frequency 10% slower ...

  • Page 30

    LTC4269-1 APPLICATIONS INFORMATION Primary Gate Delay Time (PGDLY) Primary gate delay is the programmable time from the turn-off of the synchronous MOSFET to the turn-on of the primary-side MOSFET. Correct setting eliminates overlap between the primary-side switch and secondary-side syn- ...

  • Page 31

    APPLICATIONS INFORMATION If we wanted a V -referred trip point of 36V, with 1.8V IN (5%) of hysteresis (on at 36V, off at 34.2V): 1. 529k, use 523k R A 3.4µA 523k = = 18.5k, use 18.7k R ...

  • Page 32

    LTC4269-1 APPLICATIONS INFORMATION The LTC4269-1 has an internal clamp on V mately 19.5V. This provides some protection for the part in the event that the switcher is off (UVLO low) and the V node is pulled high ...

  • Page 33

    APPLICATIONS INFORMATION Short-Circuit Conditions Loss of current limit is possible under certain conditions such as an output short-circuit. If the duty cycle exhibited by the minimum on-time is greater than the ratio of secondary winding voltage (referred-to-primary) divided by input ...

  • Page 34

    LTC4269-1 APPLICATIONS INFORMATION For each secondary-side power MOSFET, the BV be greater than: BV ≥ • N DSS OUT IN(MAX) SP Choose the primary-side MOSFET R gate drive voltage (7.5V). The secondary-side MOSFET gate drive voltage depends ...

  • Page 35

    APPLICATIONS INFORMATION The LTC4269-1 gate drives will clamp the max gate voltage to roughly 7.5V, so you can safely use MOSFETs with maximum V of 10V and larger. GS Synchronous Gate Drive There are several different ways to drive the ...

  • Page 36

    ... This heat sink should be electrically connected to GND. For optimum thermal performance, make the heat sink as large as possible. Voltages can be as large as 57V for PoE applications, so high voltage layout techniques should be employed. The SHDN SwitcherCAD is a trademark of Linear Technology Corporation. and V ) PORTN PORTP ...

  • Page 37

    APPLICATIONS INFORMATION pin should be separated from other high voltage pins, like avoid the possibility of leakage currents PORTP NEG shutting down the LTC4269-1. If not used, tie SHDN The load capacitor ...

  • Page 38

    LTC4269-1 TYPICAL APPLICATIONS 38 42691fb ...

  • Page 39

    TYPICAL APPLICATIONS V PORTP + 48V AUXILLIARY POWER – B1100 8 PLCS 107k 36V 54V FROM PDZ36B DATA PAIR 10k BSS63LT1 S1B BAS21 SMAJ58A 30.9Ω 54V FROM 0.1μF 24k SPARE PAIR 100V T1: PCA ELECTRONICS, EPC3409G-LF OR PULSE, PA2369NL T2: ...

  • Page 40

    LTC4269-1 TYPICAL APPLICATIONS V PORTP + 48V AUXILLIARY POWER – B1100 8 PLCS 107k 36V 54V FROM PDZ36B DATA PAIR 10k BSS63LT1 S1B BAS21 SMAJ58A 30.9Ω 54V FROM 0.1μF 24k SPARE PAIR 100V T1: PCA ELECTRONICS, EPC3410G-LF OR PULSE, PA2467NL ...

  • Page 41

    TYPICAL APPLICATIONS V PORTP + 48V AUXILLIARY POWER – B1100 8 PLCS 107k 36V 54V FROM PDZ36B DATA PAIR 10k BSS63LT1 S1B BAS21 SMAJ58A 30.9Ω 54V FROM 0.1μF 24k SPARE PAIR 100V T1: PCA ELECTRONICS, EPC3408G-LF OR PULSE, PA2466NL T2: ...

  • Page 42

    LTC4269-1 PACKAGE DESCRIPTION 4.50 ± 0.05 6.43 ±0.05 2.65 ±0.05 3.10 ± 0.05 0.40 BSC 6.00 REF RECOMMENDED SOLDER PAD LAYOUT APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 7.00 ±0.10 PIN 1 TOP MARK (SEE NOTE 6) 0.200 ...

  • Page 43

    ... Added Text Clarifying Connecting PWRGD Pin to UVLO Pin in Complementary Power Good Section of the Applications Information Section 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. LTC4269-1 ...

  • Page 44

    ... IEEE 802.3af PD Interface with an Integrated Switching Regulator LTC4268-1 High Power PD with Synchronous No-Opto Flyback Controller LTC4269-2 IEEE 802.3af/IEEE 802.3at PD with Synchronous Forward Controller ThinSOT is a trademark of Linear Technology Corporation. 44 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● COMMENTS ...