MCP1643 SYNCHRONOUS BOOST LED
CONSTANT CURRENT REGULATOR
EVALUATION BOARD USER’S GUIDE
2013 Microchip Technology Inc.
DS20005196A-page 11
Chapter 1. Product Overview
1.1
INTRODUCTION
This chapter provides an overview of the MCP1643 Synchronous Boost LED Constant
Current Regulator Evaluation Board and covers the following topics:
• MCP1643 Short Overview
• What is the MCP1643 Synchronous Boost LED Constant Current Regulator
Evaluation Board?
• MCP1643 Synchronous Boost LED Constant Current Regulator Evaluation Board
1.2
MCP1643 SHORT OVERVIEW
The MCP1643 is a compact, high-efficiency, fixed frequency, step-up DC-DC converter
optimized as an LED constant current generator. This product provides an easy-to-use
power supply solution, with a minimum number of external components for applications
powered by one-cell, two-cell Alkaline, NiCd or NiMH batteries.
The MCP1643 is a PWM-only device that operates at a fixed 1 MHz switching
frequency. The device has an operating input voltage range from 0.5V to 5V (with a
0.65V start-up voltage).
The LED can be turned ON and OFF with a variable duty cycle applied to the EN pin
for applications that require dimming. The maximum dimming frequency is only limited
by the internal soft-start of 240 µs.
The device is available in MSOP-8 and 2X3 TDFN-8 packages.
The scope of the MCP1643 Synchronous Boost LED Constant Current Regulator
Evaluation Board is to demonstrate the LED driving capabilities of the MCP1643 when
supplied from one AA battery.
FIGURE 1-1:
Typical MCP1643 Boost Converter Single Cell Battery Input.
V
IN
GND
V
FB
C
OUT
4.7...20
µ
F
C
IN
4.7...10
µ
F
L
1
4.7
µ
H
SW
LED
4.7
EN
V
OUT
+
-
AL
KAL
IN
E
ON
OFF
MCP1643
I
LED
=25 mA
I
LED
=
0.12V
R
SET
R
SET
