MCP165X 3W White LED Demo Board User’s Guide

DS51513A-page 8

 2004 Microchip Technology Inc.

1.4

HOW IT WORKS

1.4.1

MCP1650/1/2/3 Functions

The MCP1650/1/2/3 product family consists of four high-frequency, boost converter

devices having different combinations of features. All devices in the family feature

750 kHz high-frequency, low quiescent current, shutdown compatibility and the MSOP

package. The MCP1650 is the base device in an 8-pin MSOP package. The MCP1651

includes all of the features of the MCP1650, with the addition of a low-battery detect

and a low-battery output indicator. The MCP1652 includes all of the features of the

MCP1650, with the addition of a power good indicator. The MCP1653 has all the

features of the MCP1650/1/2 and is offered in a 10-pin MSOP package.

1.4.2

Power Topology and Output Regulation

The topology used to convert the wide ranging input voltage into a regulated output

voltage is the SEPIC topology. This topology allows the input voltage to be stepped-up

or stepped-down and provides protection if the switching FET fails.

The output current is regulated by using a sense resistor to change the white LED

current into a voltage. This voltage is then fed into the voltage reference pin on the

MCP1651R. Please refer to the MCP1650/1/2/3 data sheet (DS21876) for more

information regarding output regulation.