LTC4278 IEEE 802.3at PD with Synchronous No-Opto Flyback Controller and 12V Aux Support FEATURES DESCRIPTION n 25.5W IEEE 802.3at Compliant (Type 2) PD The LTC 4278 is an integrated Powered Device (PD) con- n 10V to 57V Auxiliary Power Input troller and switching regulator intended for high power n Shutdown Pin for Flexible Auxiliary Power Support IEEE 802.3at and 802.3af applications. With a wide input n Integrated State-of-the-Art No-Opto Synchronous voltage range, the LTC4278 is specifically designed to sup- Flyback Controller port PD applications that include a low-voltage auxiliary Isolated Power Supply Efficiency >92% power input such as a 12V wall adaptor. The inclusion of 88% Efficiency Including Diode Bridge and a shutdown pin provides simple implementation of both Hot Swap FET PoE and auxiliary dominate applications. In addition, the n Superior EMI Performance LTC4278 supports both 1-event and 2-event classifications n Robust 100V 0.7 (Typ) Integrated Hot Swap MOSFET as defined by the IEEE, thereby allowing the use in a wide n IEEE 802.3at High Power Available Indicator range of product configurations. n Integrated Signature Resistor and Programmable The LTC4278 synchronous, current mode, flyback control - Class Current ler generates multiple supply rails in a single conversion n Undervoltage, Overvoltage and Thermal Protection step providing for the highest system efficiency while main - n Short-Circuit Protection with Auto-Restart taining tight regulation across all outputs. The LTC4278 n Programmable Soft-Start and Switching Frequency includes Linear Technologys patented No-Opto feedback n Complementary Power Good Indicators topology to provide full IEEE 802.3 isolation without the n Thermally Enhanced 7mm 4mm DFN Package need of an opto-isolator circuit. A true soft-start function allows graceful ramp-up of all output voltages. APPLICATIONS The LTC4278 is available in a space saving 32-lead DFN n VoIP Phones with Advanced Display Options package. n Dual-Radio Wireless Access Points n L, LT, LTC, LTM, Linear Technology, SwitcherCAD and the Linear logo are registered PTZ Security Cameras trademarks and Hot Swap and ThinSOT are trademarks of Linear Technology Corporation. n RFID Readers All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5841643. n Industrial Controls EPC3472G-LF TYPICAL APPLICATION 25W PD Solution with 12V Auxiliary 0.18H 5V 8.2H 4.5A 47F + + + 100F AUXILIARY 10F 10F SUPPLY (10V TO 57V) 294k 21.5k BSS63 1F TO MICRO HAT2169 46.4k 3.01k CONTROLLER FDMS2572 ~ + 54V FROM PDS5100H DATA PAIR + ~ UVLO PWRGD T2P FB V PG SENSE CC V PORTP 12m SHDN R SENSE CLASS LTC4278 0.1F 24k 30.9 ~ + 54V FROM SG 2.2nF V V 1F SPARE PAIR PORTN CMP ~ V SYNC GND OSC PGDLY t ENDLY R C NEG ON CMP CMP 12k 100k 38.3k 1.8k B1100 33pF 0.1F 4278 TA01a 4278fc 1LTC4278 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1, 2) TOP VIEW Pins with Respect to V PORTN SHDN 1 32 V PORTP V Voltage ......................................... 0.3V to 100V PORTP T2P 2 31 NC V Voltage ......................................... 0.3V to V NEG PORTP R 3 30 PWRGD CLASS V Pull-Up Current ..................................................1A NEG NC 4 29 PWRGD SHDN ....................................................... 0.3V to 100V V 5 28 NC PORTN R , Voltage ............................................ 0.3V to 7V CLASS V 6 27 V PORTN NEG R Source Current ...........................................50mA CLASS NC 7 26 V NEG PWRGD Voltage (Note 3) NC 8 25 NC 33 Low Impedance Source ......V 0.3V to V +11V SG 9 24 PG NEG NEG Sink Current .........................................................5mA V 10 23 PGDLY CC t 11 22 R PWRGD, T2P Voltage ............................... 0.3V to 100V ON CMP ENDLY 12 21 C PWRGD, T2P Sink Current .....................................10mA CMP + SYNC 13 20 SENSE Pins with Respect to GND SFST 14 19 SENSE V Voltage ................................................ 0.3V to 22V CC + OSC 15 18 UVLO SENSE , SENSE Voltage ........................ 0.5V to +0.5V FB 16 17 V CMP UVLO, SYNC Voltage ...................................0.3V to V CC FB Current ..............................................................2mA DKD32 PACKAGE 32-LEAD (7mm 4mm) PLASTIC DFN V Current .........................................................1mA CMP T = 125C, = 34C/W, = 2C/W JMAX JA JC Operating Ambient Temperature Range GND, EXPOSED PAD (PIN 33) MUST BE SOLDERED TO A HEAT SINKING PLANE THAT IS CONNECTED TO V NEG LTC4278C ................................................ 0C to 70C LTC4278I..............................................40C to 85C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC4278CDKD PBF LTC4278CDKD TRPBF 4278 0C to 70C 32-Lead (7mm 4mm) Plastic DFN LTC4278IDKD PBF LTC4278IDKD TRPBF 4278 32-Lead (7mm 4mm) Plastic DFN 40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. 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