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Adding Intelligence to Lighting Applications
Generating PWM for LED Dimming and Colour Control
PWM signals can be generated using simple software techniques and I/O pins. This option is most effective when PWM frequency and duty cycle resolution requirements are not too high.
For more demanding applications there are multiple ways to generate PWM control signals to control power circuits:
• Use 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.
• An external PWM peripheral IC may be used. This option is useful when multiple high speed PWM channels are required.
A PIC® microcontroller with an on-chip comparator such as the PIC12F615 can be used to implement a simple LED driver. The PIC12HV615 adds an internal regulator, allowing operation from a DC bus higher than 5 volts.
Mixed Signal Controllers in 8/14/16-pin package
RGB Colour LED Application Using PIC12HV615
Recommended Part: |
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PIC16HV785 High Voltage 20-pin microcontroller with two comparators, SR latch and two operational amplifiers,
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Available Literature: |
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AN654 – PWM, A Software Solution using the 16CXXX Devices
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AN786 – Considerations for Driving Power MOSFETs in High-Current, Switch Mode Regulators
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Development Tools |
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