MAX1800

19-1833; Rev 0; 10/00 KIT ATION EVALU E L B AVAILA Digital Camera Step-Up Power Supply Features o +0.7V to +5.5V Input Voltage Range o Main DC-DC Converter 95% Efficiency +2.7V to +5.5V Adjustable Output Voltage 1.5A Load Current o Uncommitted Gain Block for Linear Regulator o Three Independent Auxiliary Step-Up Controllers Adjustable Maximum Duty Cycle o Oscillator and Reference Outputs to Drive External Slave Controllers (MAX1801) o Power-Ready Output o Up to 1MHz Switching Frequency o 1µA Supply Current in Shutdown Mode o Internal Soft-Start Control o Overload Protection for all DC-DC Converters o Compact 32-Pin TQFP Package (5mm x 5mm body) General Description The MAX1800 provides a complete power-supply solution for digital still cameras and video cameras. The device integrates a high-efficiency main step-up DC-DC converter, three auxiliary step-up controllers, and an uncommitted gain block that drives an external P-channel MOSFET for a linear regulator. The MAX1800 is targeted for applications that use either two or three primary cells or a single lithium-ion (Li+) battery. The main DC-DC converter accepts inputs from +0.7V to +5.5V and regulates a resistor-adjustable output from 2.7V to 5.5V. It uses an internal synchronous rectifier to regulate the output with 95% efficiency. An adjustable operating frequency facilitates designs for optimum size, cost, and efficiency. The auxiliary step-up controllers can be used to power a digital camera’s CCD, LCD, and backlight....