PIC16F1938_13 Datasheet, PDF (212/488 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver

PIC16(L)F1938/9
23.3.6 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 PRx is
255. The resolution is a function of the PRx register
value as shown by Equation 23-4.
EQUATION 23-4: PWM RESOLUTION
Resolution = ^{l--o---g----}--4---l-^_{o--P-g---R-}--2-x---_-+------1---^---^ bits
Note:
If the pulse width value is greater than the
period the assigned PWM pin(s) will
remain unchanged.
TABLE 23-5: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 32 MHz)
PWM Frequency
1.95 kHz
7.81 kHz 31.25 kHz 125 kHz
250 kHz
Timer Prescale
PRx Value
Maximum Resolution (bits)
16
0xFF
10
4
0xFF
10
1
0xFF
10
1
0x3F
8
1
0x1F
7
333.3 kHz
1
0x17
6.6
TABLE 23-6: 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
Timer Prescale
PRx Value
Maximum Resolution (bits)
16
0xFF
10
4
0xFF
10
1
0xFF
10
1
0x3F
8
1
0x1F
7
208.3 kHz
1
0x17
6.6
TABLE 23-7: 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
PRx Value
Maximum Resolution (bits)
16
0x65
8
4
0x65
8
1
0x65
8
1
0x19
6
1
0x0C
5
1
0x09
5
DS40001574C-page 212
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