5 4 3 2 1 REVISION HISTORY ECO 1 TRD1+ TRCT1 TRD1- 2 3 D TRD2+ TRCT2 IN FROM PoE+ PSE 6 TRD2- 4 TRD3+ TRCT3 5 TRD3- 7 TRD4+ TRCT4 8 TRD4VC1 VC2 VC3 VC4 APPROVED DATE RYAN H. 02-02-2012 4 6 OUT TO PHY 5 3 D 1 U2 2 VCC 8 PS2801-1-L R1 10K 7 TXCT 9 13 14 15 16 1 4 2 3 T2P E14 R8 10K RXCT C34 4.7nF 2kV SPARE2 L2 8.2uH 4 X 75 Ohms 2 J1 C6 C2 3.3uF + C5 D1 SMBJ58A 10uF R9 20K D11 BAS21 R2 47 Q3 FMMT624 + C3 C1 22uF C9 100uF C10 OPT R33 620 11 12 T1 EPC3472G-LF 3 4 D17 7.5V CMHZ4693 R10 20 +VOUT E1 1 2 R3 OPT 100V 7499511001 180nH 7 8 6 1 SHIELD SHIELD +VOUT L1 5 1nF 2kV R38 0 PRODUCTION 10 4 X 12nF C DESCRIPTION 1 12 SPARE1 18 17 REV 1 11 C7 220pF [email protected] D15 C LED GREEN -VOUT E3 C4 1nF Q2 HAT2169H AUX+ R15 10 E10 Auxiliary Supply VPORT_N VPORTN 24K 2 D13 S1B R36 30.9 1 AUXE12 A GND 3 SG PG 9 24 10 VCC 31 8 NC NC 25 NC T2P /PWRGD 2 30 29 R23 12K R24 100K 20 19 C27 1uF R16 12m 3 EPA4271GE 3 C26 33nF R27 3.3K D14 BAT54 4 R28 10K C11 OPT C33 3.3nF 2 D12 PDS5100H CUSTOMER NOTICE APPROVALS LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES. VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APP ENG. APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. TECHNOLOGY AK RYAN H. HIGH EFFICIENCY PoE+PD AND SWITCHER WITH 12V AUX SUPPORT 3 N/A SCALE = NONE 2 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only TITLE: SCHEMATIC SIZE THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 4 B 6 T2 17 R22 15 C28 2.2nF 1 GND 33 CCMP 21 SFST OSC R25 R26 1.82K 38.3K C30 C31 C32 33pF 0.1uF OPT. C24 1uF 100 D16 B1100 E13 5 +VOUT CMLT3820G 1 1 2 E11 14 C25 1nF 15 R21 VCMP ENDLY E9 R20 3.01K Q7 R17 1 UVLO 12 R19 54.9K C13 OPT SENSE- SHDN RCMP SPARE2 Q6 CMLT7820G exposed pad, solder side NC SYNC 1 18 0 SENSE+ 22 SPARE2 D9 FB 13 D6 4 BSS63LT1 R18 20K E8 16 TON SPARE1 D8 C12 OPT R12 294K Q5 PGDLY D7 1 VPORTP 11 3 3.3mH 32 23 4 E7 2 NC VNEG VNEG RXCT L3 28 27 26 1 Q1 FDMS86101 R11 1uF C19 16V PWRGD LTC4278IDKD R14 2.49K NC VPORTN VPORTN D5 RCLASS D2 B SPARE1 5.1 E6 U1 7 6 5 E4 C99 1nF 100V 3 D4 TXCT 0.1uF 100V 2 E2 3 RXCT PWRGD E5 VPORTP D3 TXCT PWRGD R37 OPT C8 8V - 57V VPORT_P R13 21.5K R34 VCC DATE: IC NO. LTC4278IDKD REV. 1 DEMO CIRCUIT 1561B Wednesday, February 01, 2012 SHEET 1 1 OF 1 A