5 4 3 2 1 REVISION HISTORY ECO REV __ DESCRIPTION 3 APPROVED JAINO P. PRODUCTION DATE 5-19-10 D D 27 E4 VOUT1 R2 21 11 E9 E10 C7 C8 1500pF 1500pF B 1 20 RST2 SYNC VOUT1 E2 E3 VOUT1 3.3V @ 0.8A GND 24 25 L2 1.0uH 6 C4 22uF 6.3V 1206 R3 49.9K 1 5 R5 49.9K 28 4 R7 49.9K C5 1000pF E5 VOUT2 1.2V @ 1A E7 GND E8 SYNC C C6 1000pF GND CWDT 3 RST1 GND 8 R1 80.6K 18 R10 100K 17 100K SS2 16 R8 WDE WDE GND 9 GND 100K 15 VOUT1R6 SS1 GND 1 ON JP1 2 FB2 WDO 23 10 FB1 26 100K SW2 WDI GND R4 E15 OFF RST2 VIN2 RT E13 13 RST1 PGOOD 29 GND DA CPOR WDO EN2 E12 E6 C3 22uF 6.3V 1206 D2 100K 14 19 U1 7 WDI L1 3.3uH SW1 LT3640EFE 12 C EN/UVLO 2 2 R13 (OPT) 1 BST 3 2 PGOOD SW VIN E11 R11 100K RUN C2 2.2uF 50V 1206 R12 301K VOUT1 GND D1 C1 0.1uF 10V VIN 22 VIN E1 5V - 35V TRANSIENT TO 55V R9 32.4K B OPTIONAL COMPONENTS L3 LPS4018-332ML FB1 VEMI GND E14 VIN OPT C10 (OPT) 0603 + C9 22uF 63V OPT C11 (OPT) 1210 E16 NOTE: UNLESS OTHERWISE SPECIFIED 1. ALL RESISTORS ARE IN 0402. ALL CAPACITORS ARE IN 0402. A CUSTOMER NOTICE LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. 2. INSTALL SHUNTS AS SHOWN. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 5 4 3 APPROVALS PCB DES. APP ENG. TECHNOLOGY HZ JAINO P. 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 DUAL MONOLITHIC STEP-DOWN SWITCHING REGULATOR WITH POWER-ON RESET AND WATCH DOG TIMER SIZE N/A SCALE = NONE 2 DATE: IC NO. REV. LT3640EFE DEMO CIRCUIT 1359A Monday, July 19, 2010 SHEET 1 1 3 OF 1 A