LM2798 Datasheet | National Semiconductor

Description The LM2797/98 switched capacitor step-down DC/DC converters efficiently produce a 120m A regulated low-voltage rail from a 2.6V to 5.5V input. Fixed output voltage options of 1.5V, 1.8V, and 2.0V are available. The LM2797/98 uses multiple fractional gain configurations to maximize conversion efficiency over the entire input voltage and output current ranges. Also contributing to high overall efficiency is the extremely low supply current of the LM2797/98: 35µA operating unloaded and 0.1µA in shutdown. Features of the LM2797/98 include input voltage and output voltage monitoring. Pin BATOK provides battery monitoring by indicating when the input voltage is above 2.85V (typ.). Pin POK verifies that the output voltage is not more than 5% (typ.) below the nominal output voltage of the part. The optimal external ponent requirements of the LM2797/98 solution minimize size and cost, making the part ideal for Li-Ion and other battery powered designs. Two 1µF flying capacitors and two 10µF bypass capacitors are all that is required, and no inductors are needed. The LM2797/98 also features short-circuit protection overtemperature protection, and soft-start circuitry to prevent excessive inrush currents. The LM2798 has a 400µs turn-on time. The turn-on time of the LM2797 is 100µs. Features n Output voltage options: 2.0V ± 5%, 1.8V ± 5%, and 1.5V ± 6% n 120m A output current capability n Multi-Gain and Gain Hopping for Highest Possible Efficiency - up to 90% Efficient n 2.6V to 5.5V input range n Input and Output Voltage Monitoring (BATOK and POK) n Low operating supply current: 35µA n Shutdown supply current: 0.1µA n Thermal and short circuit protection n LM2798 turn-on time: 400µs LM2797 turn-on time: 100µs n Available in an 10-Pin MSOP Package Applications n n n n n Cellular Phones Pagers H/PC and P/PC Devices Portable Electronic Equipment Handheld Instrumentation Typical Application Circuit © 2003 National Semiconductor Corporation DS200445 .nation...