Control LEDs with PWM

There are multiple ways to generate Pulse Width Modulation (PWM) control signals to control power circuits such as an LED driver.

  • 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 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.
  • An external PWM peripheral IC may be used. This option is useful when additional 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 has an internal regulator, allowing operation from a DC bus that is higher than 5 V.

8, 14 and 20-Pin PIC® Microcontroller Mixed Signal Features

Device Pins Voltage Reference Comparator Op Amps ADC Digital PWM Module PWM SR Latch
PIC12F609/PIC12HV609 8 1
PIC12F615/PIC12HV615 8 1 10-bit 1
PIC12F1822 8 Yes 1 10-bit 1 1
PIC16F610/PIC12HV610 14 2 1
PIC16F616/PIC16HV616 14 2 10-bit 1 1
PIC16F785/PIC16HV785 20 Yes 2 2 10-bit 1 2
PIC16F1828 20 Yes 2 10-bit 4 1

‘HV’ part numbers have internal shunt voltage regulator.

Buck LED Driver Using a PIC12HV615 On-chip Comparator


RGB Color LED Application Using PIC12HV615

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