Product Overview
2020 Microchip Technology Inc.
DS50002945A-page 11
1.5
FUNCTIONAL DESCRIPTION
The MCP1633 device provides all the analog functions necessary to implement a
stand-alone LED driver. When combined with an external microcontroller, the
MCP1633 device can be used to implement different intelligent converters, similar to
those necessary for LED drivers.
The power train of this application uses the Single-Ended Primary Inductor Converter
(SEPIC) topology.
The converter provides constant current with limited voltage at the output, necessary
for LED driver applications. The average current in the L1B inductor, which is also the
output current of the converter, is sensed using a 0.1
shunt resistor (RS). As the
voltage across the shunt resistor is negative, the internal amplifier is set to -10x gain
and the output is connected to the FB pin. The conversion gain of this circuit is 1V/A.
The output current is set by R
VREF
.
Output current can be calculated with
.
EQUATION 1-1:
1.6
WHAT DOES THE MCP1633 DEMONSTRATION BOARD KIT INCLUDE?
The MCP1633 Demonstration Board kit includes:
• MCP1633 SEPIC LED Driver Demonstration Board (ADM01002)
• Important Information Sheet
I
OUT
V
REF
R2
R2 R1
=
Where:
V
REF
I
OUT RS
R2 R1
200 mV
=
=
R
VREF
V
REF
50
A
4 k
=
=
