Datasheet

© 2007 Microchip Technology Inc. DS41250F-page 217
PIC16F913/914/916/917/946
15.3.3 PWM RESOLUTION
The resolution determines the number of available duty
cycles for a given period. For example, a 10-bit resolution
will result in 1024 discrete duty cycles, whereas an 8-bit
resolution will result in 256 discrete duty cycles.
The maximum PWM resolution is 10 bits when PR2 is
255. The resolution is a function of the PR2 register
value as shown by Equation 15-4.
EQUATION 15-4: PWM RESOLUTION
TABLE 15-3: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (F
OSC = 20 MHz)
TABLE 15-4: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (F
OSC = 8 MHz)
Note: If the pulse width value is greater than the
period the assigned PWM pin(s) will
remain unchanged.
Resolution
4PR2 1+()[]log
2()log
------------------------------------------ bits=
PWM Frequency 1.22 kHz 4.88 kHz 19.53 kHz 78.12 kHz 156.3 kHz 208.3 kHz
Timer Prescale (1, 4, 16) 16 4 1 1 1 1
PR2 Value 0xFF 0xFF 0xFF 0x3F 0x1F 0x17
Maximum Resolution (bits) 10 10 10 8 7 6.6
PWM Frequency 1.22 kHz 4.90 kHz 19.61 kHz 76.92 kHz 153.85 kHz 200.0 kHz
Timer Prescale (1, 4, 16) 16 4 1 1 1 1
PR2 Value 0x65 0x65 0x65 0x19 0x0C 0x09
Maximum Resolution (bits) 8 8 8 6 5 5