DC308 INTRODUCTION Description The LTC3401 is a high efficiency, step-up DC/DC converter that starts up from an input voltage as low as 1V. Once it is running, the LTC3401 is supplied from the output voltage and the input voltage can go well below 1V. The device includes a 0.16 N-channel MOSFET and a 0.18 P- channel synchronous rectifier, resulting in higher than 90% efficiency in many applications. Switching frequencies up to 3MHz can be programmed with an external resistor the part can also be synchronized to an external clock. Demonstration Circuit DC308 consists of two step-up converters using LTC3401. The top circuit runs at 3MHz it is designed for minimum board size. This circuit is suitable for one cell to 3.3V applications where size is critical. The bottom circuit is a 1MHz converter, which gives a good trade-off between efficiency and size. The output voltage of the bottom circuit is jumper selectable between 3.3V and 5V. Quick Start Guide 1. Apply a voltage source to the input of the circuit between the V and GND terminals. The IN circuit will start up at input voltage higher than 1V. Do not apply more than 5V to the input. Note that the boost circuit will regulate the output only when the input voltage is less than the desired output voltage. 2. Attach a voltmeter or oscilloscope probe between the V and GND terminals of the circuit OUT to monitor the output. To start the circuit, remove the shunt that ties the shutdown pin to the GND. 3. Attach a load to the output. The available output power depends on the input voltage. Please refer to the performance summary for maximum current at different input and output voltages. 4. Proper hook-up is essential for accurate and meaningful evaluation of efficiency and regulation. Figure 1 shows the appropriate arrangement of supply, load, ammeters and voltmeters. some invisible text some invisible text LTC3401EMS10 DEMO CIRCUIT DC308 I 3MHz Single Cell Boost Regulator I IN OUT +V +V IN OUT E4 E1 + BENCH V V LOAD IN OUT SUPPLY GND GND E2 E3 1MHz High Efficiency Synchronous Boost Regulator I I IN OUT +V +V IN OUT E5 E8 + BENCH LOAD V V IN OUT GND GND SUPPLY E6 E7 Figure 1. DC308 Hookup Diagram PERFORMANCE SUMMARY PARAMETER CONDITION VALUE 1MHz Boost Converter Maximum Load Current, Min 175mA V = 3.3V, V = 0.9V OUT IN 395mA V = 3.3V, V = 1.8V OUT IN 240mA V = 5.0V, V = 1.8V OUT IN 370mA V = 5.0V, V = 2.7V OUT IN 3MHz Boost Converter Maximum Load Current, Min 130mA V = 3.3V, V = 0.9V OUT IN + +