DC422 Demo Board Quick Start Guide Demonstration circuit DC422 is a constant-frequency step-down converter, using the LTC3405 monolithic synchronous buck regulator. The DC422 has an input voltage range of 2.65V to 6V, and is capable of delivering up to 250mA of output current at 1.8V. In Burst Mode , the DC supply current is typically only 25A at no load, and less than 1A in shutdown. For switching-noise-sensitive applications, turn off Burst Mode by pulling the MODE pin up to V (jumper JP1 in upper position). IN The DC422 demo board features the LTC3405 in a tiny 6-Pin SOT-23 package, operating at 1.5 MHz. This allows the use of low profile surface mount components, ideal for battery-powered, handheld applications. Gerber files for this circuit are available by calling Linear Technology Corporation at (408) 432-1900. Quick Start Procedure Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: Note Be careful about which side of the board you use for input, and which you use for output. When the board is right side up (the title is at the top of the board), the output voltage turret is on the left side of the board, and the input voltage turret is on the right side of the boardopposite of what you might expect. 1. Connect the input power supply to the V and GND terminals on the right side of the IN board. Note Do not hot-plug V above 5.5V or increase V over the rated maximum IN IN supply voltage of 6V. Either condition could damage the part. 2. Connect the load between the V and GND terminals on the left side of the board. OUT 3. Select the desired operating mode using JP1. To select pulse-skipping mode, tie the MODE pin to V by inserting the jumper into IN the lower position. To select Burst Mode connect the MODE pin to ground by inserting the jumper into the upper position. Note Do not leave this pin floating. 4. To shut down the circuit, pull the RUN pin to ground by inserting jumper JP2 into the upper position. DC422 Demo Board Quick Start Guide Page 1 of 2 LTC3405ES6 High Efficiency, SOT-23 Synchronous Buck Regulator Demo Circuit DC422 + + JP2 JP1 Vout Vin + LOAD GND GND GND GND Linear Technology (408) 432-1900 www.linear-tech.com Figure 1. Proper Measurement Equipment Setup DC422 Demo Board Quick Start Guide Page 2 of 2 + + +