DC348A Introduction Description Demonstration circuit DC348 demonstrates the low power LTC1878 monolithic synchronous regulator in a power supply optimized for cellular phone applications. The LTC1878 is ideal for this application because of its 550kHz switching frequency, low quiescent current (power) consumption, and small package size (MSOP). The DC supply current is typically 10A at no load and less than 1A in shutdown. The high switching frequency allows the use of tiny surface mount components. With an input voltage range of 2.65V to 6V, the LTC1878 is ideally suited for Lithium-Ion Battery applications. Quick Start Guide It is easy to set up DC348 to evaluate the performance of the LTC1878. Please follow the procedure outlined below for proper operation. 1. Connect the input power supply to the VIN and GND terminals. Refer to Figure 1 for proper measurement equipment setup. 2. Connect the load between the VOUT and GND terminals. 3. To shut down the circuit, connect the RUN/SS pin to ground. 4. For synchronized operation, connect the clock signal between the SYNC and GND terminals RUN + - VIN LTC1878EMS8 High Efficiency Monolithic Synchronous Step-Down Regulator Demo Circuit DC348A SYNC + VOUT + + + - - - - LOAD GND GND Figure 1. DC348A Hook-up Diagram 1 2 3 E3 RUN E1 U1 Cc A L1 PCB SILKSCREEN GND Cin 4.7 uF, 6.3V Cc Optional Rc Optional Rfar2 100K SYNC E6 Rfar1 100K B Cith 220 pF 1 2.7V - 5V 8 PLL LPF RUN E2 7 SYNC Ith 2 VIN B 3 4 Rc Cin Cith Rfb1 Rfb2 Cffw 6 Vin Vfb A Cout 5 SW GND 4 U1 LTC1878 Cout 22uF 6.3V 412K 280K 2.5 3.3 C 1M 1.5 Vout(V) Rfb1(ohms) 4.7 uH L1 C Cffw 22 pF E4 GND 1.8V @ 200 mA (max) E5 VOUT E D Wednesday, January 31, 2001 Date: Sheet 1 E DEMO DC348A LTC1878EMS8 Document Number Size of High Efficiency Monolithic Synchronous Step-Down Regulator Title 1630 McCarthy Blvd. Milpitas, CA 95035 (408) 432-1900 (408) 434-0507 FAX LINEAR TECHNOLOGY CORPORATION 715k, 1% Rfb1 Rfb2 887k, 1% D 1 A Rev 1 2 3 4 Bill Of Material Demo Bd. #348A Linear Technology Corporation LTC1878 6/16/2005 12:54 PM Item Qty Reference 1 2 3 4 5 6 7 8 9 10 11 12 1 1 1 1 1 1 2 1 1 1 6 1 Cffw Cin Cith Cout Cc L1 Rfar1,Rfar2 Rfb1 Rfb2 Rc E1,E2,E3,E4,E5,E6 U1 Part Description CAP., NPO 22pF 25V, 0402 CAP., X5R 4.7uF, 6.3V, 0805 CAP., X7R 220pF, 16V, 0402 CAP., X5R 22uF, 6.3V 1210 Optional INDUCTOR, SMD 4.7 uH RES.,CHIP 100K, 1/16W 5% 0603 RES.,CHIP 715K, 1/16W 1% 0402 RES.,CHIP 887K, 1/6W 1% 0402 Optional TURRET I.C., LTC1878EMS8 Manufacture Part# AVX, 04023A220JAT1A TAIYO YUDEN, JMK212BJ475MG AVX, 0402YC221KAT1A MURATA, GRM42-2X5R226K6.3 TAIYO YUDEN, LB2016T4R7K AAC, CR16-104JM AAC, CR05-7153FM AAC, CR05-8873FM MILL-MAX, 2501-2 LINEAR, LTC1878EMS8 PAGE 1 OF 1