MCP165X 3W WHITE LED
DEMO BOARD USER’S GUIDE
2004 Microchip Technology Inc. DS51513A-page 5
Chapter 1. Product Overview
1.1 INTRODUCTION
The MCP1650/1/2/3 Boost Controller family is a 750 kHz gated oscillator controller in
an 8 or 10-pin MSOP package. The family includes peak current limit, adjustable output
voltage/current, low battery detection and power good indication.
This board uses Microchip Technology’s MCP1650/1/2/3 boost controller as a
constant-current source to drive a 3W white LED. The application features the
MCP1651R-option (8-pin MSOP) with the low-battery detect feature. The input voltage
for the MCP165X 3W White LED Demo Board is 2.0V to 4.5V and the output current is
set at 700 mA.
1.2 EVALUATION BOARD DESCRIPTION
The MCP165X 3W White LED Demo Board is fully assembled, tested and ready for
evaluation and demonstration. This board is capable of functioning without any extra
lab supplies or loads. A three-socket AA battery holder is attached to the board. How-
ever, there are terminals provided to allow the use of an external voltage supply. The
input is fused for overcurrent protection.
If an external voltage supply is used, the MCP165X 3W White LED Demo Board
requires 2.0V to 4.5V for proper operation. Connect the positive terminal of the external
supply to TP1 and the ground terminal of the external supply to TP2. Care must be
taken so that the input voltage does not exceed the maximum voltage rating of 6.0V
that is specified in the MCP1650/1/2/3 data sheet (DS21876). The MCP1651R is the
specific device used on the board.
There are two switches on the board. Switch S
1
is an on/off switch used to disconnect
the input voltage. Switch S
2
is a momentary switch that triggers the PIC10F206
microcontroller to activate the Demonstration mode or the Flashing mode.
Section 1.3 “How it is used” describes how to put the MCP165X 3W White LED
Demo Board in the different modes of operation. The flowchart in Figure 1-1 shows the
sequence of events triggered by pressing the momentary switch.
The Flashing mode consists of three different operating states for the LED. The bright-
ness of the LED is approximately 50% dimmed in the first state. This is accomplished
by applying a 50% square wave to the shutdown pin of the MCP1651R. The second
and third states of operation consist of flashing the LED at two different rates. The
second state is a fast flash rate, while the third state is a slow flash rate. These rates
of flash are predetermined and are accomplished by toggling the shutdown pin with a
square wave.
The Demonstration mode automatically cycles through the three flashing modes.
