5v/3.3v/3v/adjustable-output, Step-up/step-down Dc-dc Converters

The MAX877 MAX878 MAX879 are pulse-skipping, step- up Step-down DC-DC Converters that provide a regulated output from inputs both above and below the output. They require only three external componentsan inductor (typically 22H) and two Filter capacitors. The MAX877 delivers a regulated 5V output from 2.5V to 6.2V inputs. The MAX878 generates pin-selectable volt- ages of 3.0V or 3.3V from 1.5V to 6.2V inputs. The MAX879 output CAN be adjusted from 2.5V to 6V via an external resistor divider from 2.5V to 6.2V inputs. A unique high-power, internal, synchronous Rectifier design (Active Rectifier) enables the devices to regulate in a switched linear mode if the input voltage is higher than the desired output voltage. When the input voltage falls below the output voltage, the MAX877 MAX878 MAX879 will smoothly Switch into a pulse-skipping boost mode and step up from input voltages as low as 1V. In shutdown, the active Rectifier disconnects the output from the source. This stops the current drain from input to output associated with conventional Step-up converters. High-frequency operation (up to 300kHz) allows the use of small surface-mount inductors. Supply current is 195A under no load, and only 20A in shutdown mode. For 1-cell (1V) Step-up converters with similar performance and the same pinout, refer to the MAX777/MAX778/MAX779 data sheet. By Maxim Integrated Products