PIC18LF24K Datasheet, PDF (279/594 Pages) –

PIC18(L)F26/45/46K40
22.1.5 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 ten bits when PR2 is
255. The resolution is a function of the PR2 register
value as shown by Equation 22-4.
EQUATION 22-4: PWM RESOLUTION
Resolution = ^{l--o---g----}--4---l-^_{o--P-g---R-}--2-2---_--+-----1----^--^ bits
Note:
If the pulse-width value is greater than the
period the assigned PWM pin(s) will
remain unchanged.
TABLE 22-1: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 20 MHz)
PWM Frequency
0.31 kHz
4.88 kHz
19.53 kHz 78.12 kHz 156.3 kHz
Timer Prescale
PR2 Value
Maximum Resolution (bits)
64
0xFF
10
4
0xFF
10
1
0xFF
10
1
0x3F
8
1
0x1F
7
208.3 kHz
1
0x17
6.6
TABLE 22-2: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 8 MHz)
PWM Frequency
0.31 kHz
4.90 kHz
19.61 kHz 76.92 kHz 153.85 kHz
Timer Prescale
PR2 Value
Maximum Resolution (bits)
64
0x65
8
4
0x65
8
1
0x65
8
1
0x19
6
1
0x0C
5
200.0 kHz
1
0x09
5
22.1.6 OPERATION IN SLEEP MODE
In Sleep mode, the TMR2 register will not increment
and the state of the module will not change. If the
PWMx pin is driving a value, it will continue to drive that
value. When the device wakes up, TMR2 will continue
from its previous state.
22.1.7
CHANGES IN SYSTEM CLOCK
FREQUENCY
The PWM frequency is derived from the system clock
frequency (FOSC). Any changes in the system clock
frequency will result in changes to the PWM frequency.
Refer to Section 4.0 “Oscillator Module (with
Fail-Safe Clock Monitor)” for additional details.
22.1.8 EFFECTS OF RESET
Any Reset will force all ports to Input mode and the
PWM registers to their Reset states.
 2016 Microchip Technology Inc.
Preliminary
DS40001816C-page 279