AC162078 Microchip Technology, AC162078 Datasheet - Page 129

• Manufacturer Part Number: AC162078
• Description: HEADER INTRFC MPLAB ICD2 18F1330
• Manufacturer: Microchip Technology

Specifications of AC162078

• Accessory Type: Transition Header
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: ICD2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Not applicable / Not applicable

14.5
The PWM period is defined by the PTPER register pair
(PTPERL and PTPERH). The PWM period has 12-bit
resolution by combining 4 LSBs of PTPERH and 8 bits
of PTPERL. PTPER is a double-buffered register used
to set the counting period for the PWM time base.
The PTPER buffer contents are loaded into the PTPER
register at the following times:
• Free-Running and Single-Shot modes: When the
• Continuous Up/Down Count modes: When the
The PWM period can be calculated from the following
formulas:
EQUATION 14-1:
EQUATION 14-2:
The PWM frequency is the inverse of period; or
EQUATION 14-3:
 2009 Microchip Technology Inc.
PTMR register is reset to zero after a match with the
PTPER register.
PTMR register is zero. The value held in the PTPER
buffer is automatically loaded into the PTPER
register when the PWM time base is disabled
(PTEN = 0). Figure 14-9 and Figure 14-10 indicate
the times when the contents of the PTPER buffer
are loaded into the actual PTPER register.
PWM Period
PWM Frequency =
T
T
PWM
PWM
=
=
(PTPER + 1) x PTMRPS
(2 x PTPER) x PTMRPS
PWM PERIOD FOR
FREE-RUNNING MODE
PWM PERIOD FOR
CONTINUOUS UP/DOWN
COUNT MODE
PWM FREQUENCY
F
F
OSC
PWM Period
OSC
4
/4
1
The maximum resolution (in bits) for a given device
oscillator and PWM frequency can be determined from
the following formula:
EQUATION 14-4:
The PWM resolutions and frequencies are shown for a
selection of execution speeds and PTPER values in
Table 14-2. The PWM frequencies in Table 14-2 are
calculated for Edge-Aligned PWM mode. For Center-
Aligned
approximately one-half the values indicated in this
table.
TABLE 14-2:
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
25 MHz
25 MHz
25 MHz
10 MHz
10 MHz
10 MHz
Note:
5 MHz
5 MHz
5 MHz
4 MHz
4 MHz
4 MHz
F
OSC
PIC18F1230/1330
mode,
For
frequencies will be approximately 1/2 the
value indicated in the table.
MIPS
6.25
6.25
6.25
1.25
1.25
1.25
PWM Frequency = 1/T
2.5
2.5
2.5
10
10
10
10
10
10
10
10
10
1
1
1
Resolution =
EXAMPLE PWM
FREQUENCIES AND
RESOLUTIONS
center-aligned
the
PTPER
0FFFh
07FFh
03FFh
01FFh
0FFFh
03FFh
0FFFh
03FFh
0FFFh
03FFh
0FFFh
03FFh
Value
FFh
FFh
7Fh
3Fh
1Fh
0Fh
FFh
FFh
FFh
PWM RESOLUTION
PWM
log
Resolution
log(2)
14 bits
13 bits
12 bits
11 bits
10 bits
14 bits
12 bits
10 bits
14 bits
12 bits
10 bits
14 bits
12 bits
10 bits
14 bits
12 bits
10 bits
PWM
9 bits
8 bits
7 bits
6 bits
frequencies
F
F
PWM
OSC
operation,
DS39758D-page 129
PWM
Frequency
156.2 kHz
312.5 kHz
19.5 kHz
39.0 kHz
78.1 kHz
24.4 kHz
625 kHz
2.4 kHz
4.9 kHz
9.8 kHz
1.5 kHz
6.1 kHz
2.4 kHz
9.8 kHz
1.2 kHz
4.9 kHz
3.9 kHz
976 Hz
610 Hz
305 Hz
244 Hz
PWM
will
PWM
be