Part Details for MAX668 by Maxim Integrated Products

The MAX668/MAX669 constant-frequency, pulse-width modulating (PWM), current-mode DC-DC controllers are designed for a wide range of DC-DC conversion applications, including step-up, SEPIC, flyback, and isolated-output configurations. Power levels of 20W or more can be controlled with conversion efficiencies of over 90%. The input voltage range of 1.8V to 28V supports a wide range of battery and AC-powered inputs. An advanced BiCMOS design features low operating current (220μA), adjustable operating frequency (100kHz to 500kHz), soft-start, and a SYNC input, allowing the MAX668/MAX669 oscillator to be locked to an external clock.<p>The MAX669 is optimized for low input voltages with a guaranteed start-up voltage of 1.8V. It requires bootstrapped operation (IC-powered from boosted output) and supports output voltages of up to 28V. The MAX668 operates with inputs as low as 3V and can be connected in either a bootstrapped or non-bootstrapped (IC-powered<p>from input supply or other source) configuration. When not bootstrapped, it has no restriction on output voltage. Both ICs are available in an extremely compact 10-pin μMAX® package.<p>Key Features<p>1.8V Minimum Start-Up Voltage (MAX669)<p>Wide Input Voltage Range (1.8V to 28V)<p>Tiny 10-Pin μMAX Package<p>Current-Mode PWM and Idle Mode Operation<p>Adjustable 100kHz to 500kHz Oscillator or SYNC Input<p>220μA Quiescent Current<p>Logic-Level Shutdown<p>Soft-Start

This document details the Oceanside (MAXREFDES9#) subsystem reference design, a 3.3V to 15V input, &#177;15V (&#177;12V) output, isolated power supply. The Oceanside design includes a high-efficiency step-up controller, a 36V H-bridge transformer driver for isolated supplies, a wide input range, and a pair of adjustable output low dropout (LDO) linear regulator. Test results and hardware files are included.