5 4 3 2 1 VIN1 D VIN1 7V TO 40V TRANSIENT TO 60V E1 D + E3 GND C1 10uF 63V E8 1 EN 15 E7 3 2 VOUT1 3 DIS JP1 2 IN1 BOOST EN SW U1 LT3668EMSE R5 150k 14 R8 VOUT1 R19 C EN2 DIS R20 200k 200k 1 4 174k 1% DA 1 PG 16 12 R10 3 1.50k 1% JP3 VOUT2 EN3/ILIM3 ADJ2 2 R12 EN GND ADJ3 OUT3 IN3/BD 17 7 6 5 1.50k 1% JP4 ADJ3 C14 VOUT1_5V B 47nF R17 C7 10µF 10V 1206 9 C17 (Opt) 0603 VOUT3 R13 E11 GND 0 Ohm R18 E15 E2 IN3/BD C10 1µF (Opt) VOUT3 C19 1206 (OPT) MMZ1608S601AT 0603 (OPT) VIN1_EMI C12 OPT E14 VIN1 GND 4.7uH C20 CDRH2D18/LDNP‐4R7NC Sumida 1206 (OPT) (OPT) 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. A NOTE: UNLESS OTHERWISE SPECIFIED 1. ALL RESISTORS ARE 0603 ALL CAPACITORS ARE 0603 TECHNOLOGY 4 3 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 40V STEP‐DOWN REGULATOR WITH DUAL TRACKING LDOs SIZE THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 5 E13 VOUT3 5V / 200mA C11 10µF 10V 1206 EMI Filter L2 B + C16 C18 (Opt) 0603 FB1 VOUT2 5V / 200mA C8 OPT 0 Ohm 0 Ohm E18 E10 10 1 C (Opt) 0 Ohm E17 47nF 3 IN2 + C15 ADJ2 EN3 E6 GND EN2/ILIM2 OUT2 13 * C6 0.1uF R6 11 E12 DIS R1 243k 1% VOUT1_5V VOUT1 6V / C5 22µF 25V 1210 E16 C9 1µF EN3 / ILIM3 C13 C4 22pF E4 931k 1% R9 294k 1% RT IN2 VOUT1 R7 8 E9 2 EN FB1 fs=600KHz EN2 / ILIM2 L1 27µH CDRH5D28RHPNP‐270M D1 DFLS160‐7 E5 PG * SEE DEMO MANUAL FOR CURRENT CAPABILITY 0.22µF EN VIN1 ENABLE C3 C2 2.2µF 100V 1206 GND N/A DATE: IC NO. REV. LT3668EMSE DC2243A 3 SHEET Wednesday, January 21, 2015 1 1 OF 1 A