Installation and Operation

© 2005 Microchip Technology Inc.

DS51581A-page 9

2.3.2

Evaluating the Application

The MCP1650 SEPIC Demo Board can be used to provide a low-cost, minimal size,

low-power bias circuit. A well-regulated 5V at 160 mA output is produced from a 3.0V

to 7.0V input source. This voltage range allows the source to be a single Li-Ion battery

or three to four NiMH batteries.

The SEPIC topology is employed to convert this wide-ranging input source to a

well-regulated 5 volts. The SEPIC has the ability to automatically buck or boost the

input source. By coupling the two inductors onto one magnetic core, a small footprint,

low parts-count, low-power step-up or step-down converter is developed.

To truly evaluate the effectiveness of the MCP1650 SEPIC Demo Board, the input volt-

age must be varied over the entire operating range, while the load is varied from 0A to

160 mA. Test points are provided for connecting the variable input voltage source (TP1

and TP2) and a variable load (TP4 and TP5). An additional test point (TP3) is con-

nected to the shutdown pin (SHDN) of the MCP1650. On the board, the SHDN pin is