Microchip Technology APGRD004 Data Sheet

www.microchip.com/lighting 

LED Lighting Solutions Design Guide

         

   

There are multiple ways to generate PWM control signals to 
control power circuits. 

■ 

Devices with the Capture-Compare-PWM (CCP) module 
can generate PWM signals to control power circuits using 
an on-chip digital timebase. The signal pulse width is 
controlled by the MCU clock and a duty cycle register.

■ 

The Enhanced CCP (ECCP) module allows one PWM signal 
to control 2 or 4 output pins for half-bridge or H-bridge 
control, respectively.

■ 

Devices that have a comparator and the ECCP module 
can use the comparator signal to control the turn-off time 
of the PWM signal.

■ 

Devices with comparators and a PWM SR latch can use 
comparator signals and/or clock pulses to turn the latch 
output on and off.

V

DD

Buck Topology
Driver

Drive
Level

-

+

V

SS

V

BUS

–

+

Comparator

■ 

An external PWM peripheral IC may be used. This option 
is useful when multiple high speed PWM channels are 
required.

■ 

PWM signals can be generated using software and I/O 
pins. This option is less costly when PWM frequency and 
duty cycle resolution requirements are not too high.

A PIC microcontroller with an on-chip comparator such as 
the PIC12F609 can be used to implement a simple LED 
driver. The PIC12HV609 adds an internal regulator, allowing 
operation from a DC bus higher than 5 volts.

■ 

AN874 – Buck Configuration High-Power LED Driver,

 DS00874

■ 

AN1074 – Software PWM Generation for LED Dimming

 

and RGB Color Applications, DS01074

ADC Input

Color Set

RGB LED

50 mA

User

Interface

V

IN