PIC16F/LF1946/47
22.3.6
PWM RESOLUTION
EQUATION 22-4: 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.
log4PRx + 1
Resolution = ----------------------------------------- bits
log2
The maximum PWM resolution is 10 bits when PRx is
255. The resolution is a function of the PRx register
value as shown by Equation 22-4.
Note:
If the pulse width value is greater than the
period the assigned PWM pin(s) will
remain unchanged.
TABLE 22-4: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 32 MHz)
PWM Frequency
1.95 kHz
7.81 kHz
31.25 kHz
125 kHz
250 kHz
333.3 kHz
Timer Prescale (1, 4, 16)
PRx Value
16
0xFF
10
4
1
1
0x3F
8
1
0x1F
7
1
0xFF
10
0xFF
10
0x17
6.6
Maximum Resolution (bits)
TABLE 22-5: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 20 MHz)
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)
PRx Value
16
0xFF
10
4
1
1
0x3F
8
1
0x1F
7
1
0xFF
10
0xFF
10
0x17
6.6
Maximum Resolution (bits)
TABLE 22-6: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 8 MHz)
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)
PRx Value
16
0x65
8
4
0x65
8
1
0x65
8
1
0x19
6
1
0x0C
5
1
0x09
5
Maximum Resolution (bits)
DS41414A-page 214
Preliminary
2010 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
