DC348A Analog Devices

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 V and GND terminals. Refer to Figure 1 for IN proper measurement equipment setup. 2. Connect the load between the V and GND terminals. OUT 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 LTC1878EMS8 RUN SYNC High Efficiency Monolithic Synchronous Step-Down Regulator Demo Circuit DC348A VIN VOUT + + + + LOAD GND GND Figure 1. DC348A Hook-up Diagram +A B C D E 4 4 E2 E5 L1 VOUT VIN 1.8V 2.7V - 5V 4.7 uH 200 mA (max) Rfar1 Cffw Rfb2 100K Cout E6 Cin 22 pF 887k, 1% 22uF 4.7 uF, 6.3V 6.3V SYNC E3 GND Rfar2 U1 100K LTC1878 3 3 E1 RUN Cith Rc 220 pF Optional Rfb1 715k, 1% E4 Cc GND Optional 2 2 Vout(V) Rfb1(ohms) 1.5 1M 2.5 412K PCB SILKSCREEN 3.3 280K L1 U1 LINEAR TECHNOLOGY CORPORATION 1630 McCarthy Blvd. Milpitas, CA 95035 1 1 (408) 432-1900 (408) 434-0507 FAX Cc Title High Efficiency Monolithic Synchronous Step-Down Regulator Size Document Number Rev DEMO DC348A LTC1878EMS8 A Date: Sheet of Wednesday, January 31, 2001 11 A B C D E Rc Cith Rfb1 Rfb2 Cffw Cin Cout 1 8 RUN PLL LPF 2 7 Ith SYNC 3 6 Vfb Vin 4 5 GND SW