LT4295 IEEE 802.3bt PD Interface with Forward/Flyback Controller FEATURES DESCRIPTION n IEEE 802.3af/at/bt Powered Device (PD) with The LT 4295 is an IEEE 802.3af/at/bt-compliant powered Forward/Flyback Controller device (PD) interface controller with a switching regulator n Supports Up to 71.3W PDs controller. The T2P output indicates the number of clas- n 5-Event Classification Sensing sification events received during IEEE 802.3bt-compliant n Superior Surge Protection (100V Absolute Maximum) mutual identification and negotiation of available power. n Wide Junction Temperature Range (40C to 125C) The LT4295 supports both forward and flyback power n >94% End-to-End Efficiency with LT4321 Ideal Bridge supply topologies. The flyback topology supports No-Opto n External Hot Swap N-Channel MOSFET for Lowest feedback. Auxiliary input voltages can be accurately sensed Power Dissipation and Highest System Efficiency with just a resistor divider connected to the AUX pin. n No-Opto Flyback Operation n The LT4295 utilizes an external, low R N-channel Auxiliary Power Support as Low as 9V DS(on) n ++ hot swap MOSFET and supports the LT4320/LT4321 ideal Easy Migration of LTPoE PDs to IEEE 802.3bt PDs n diode bridges, to extend the end-to-end power delivery Pin Compatible with LT4276A/B/C n efficiency and eliminate costly heat sinks. 28-Lead 4mm 5mm QFN Package The LT4295 also includes an on-chip detection signature APPLICATIONS resistor, thermal protection, slope compensation, and n many user configurable settings including classification High Power Wireless Data Systems n signature, inrush current, switcher frequency, gate drive Outdoor Security Camera Equipment n delay, soft-start and load compensation. Commercial and Public Information Displays n All registered trademarks and trademarks are the property of their respective owners. High Temperature Applications TYPICAL APPLICATION IEEE 802.3bt 71.3W (Class 8) PD Controller and Power Supply in Forward Mode + AUX Single-Signature 37V TO 57V Power Classification + + (at PD Input) V PORT 22F + 5V FMMT723 CLASS POWER 13A 0.1F 100H 3.3k 0 13W 10nF BAV19WS 10F 1 3.84W (T 50ns) RR VPORT HS V HS SW V FFS PG IN CC 2 6.49W GATE SRC VCC DLY V CC + AUX ISEN 3 13W 20m LT4295 ISEN 4 25.5W RCLASS SG ++ 5 40W RCLASS 100pF 0.1F 10k GND FB31 SS ROSC T2P ITHB 6 51W 7 62W 100k OPTO TO MICROPROCESSOR 8 71.3W 4295 TA01 Rev. B 1 Document Feedback For more information www.analog.comLT4295 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1, 2) VPORT, HSSRC, V Voltages .................. 0.3V to 100V IN TOP VIEW HSGATE Current.................................................. 20mA V Voltage .................................................. 0.3V to 8V CC ++ RCLASS, RCLASS 28 27 26 25 24 23 GND 1 22 DNC Voltages .............................. 0.3V to 8V (and VPORT) AUX 2 21 V CC SFST, FFSDLY, ITHB, T2P Voltages ... 0.3V to V +0.3V CC ++ RCLASS 3 20 PG + ISEN , ISEN Voltages ...........................................0.3V 29 RCLASS 4 19 GND GND FB31 Voltage ..................................................+12V/30V T2P 5 18 SG ++ + RCLASS/RCLASS Current .............................. 50mA V 6 17 ISEN CC AUX Current ........................................................ 1.4mA V 7 16 ISEN CC V 8 15 RLDCMP ROSC Current ..................................................... 100A CC 9 10 11 12 13 14 RLDCMP Current ................................................500A T2P Current .........................................................2.5mA Operating Junction Temperature Range (Note 3) UFD PACKAGE 28-LEAD (4mm 5mm) PLASTIC QFN LT4295I ................................................40C to 85C T = 150C, = 3.4C/W JMAX JC LT4295H ............................................ 40C to 125C EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB Storage Temperature Range .................. 65C to 150C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT4295IUFD PBF LT4295IUFD TRPBF 4295 28-Lead (4mm 5mm) Plastic QFN 40C to 85C LT4295HUFD PBF LT4295HUFD TRPBF 4295 28-Lead (4mm 5mm) Plastic QFN 40C to 125C Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with TRMPBF suffix. Rev. B 2 For more information www.analog.com V VPORT CC ROSC NC SFST HSGATE FFSDLY HSSRC ITHB V IN FB31 SWVCC