PIC18F2682-I/PT MICROCHIP [Microchip Technology], PIC18F2682-I/PT Datasheet - Page 337

• Manufacturer Part Number: PIC18F2682-I/PT
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with ECAN Technology, 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

Table 23-3 shows the relation between the clock
generated by the PLL and the frequency error from jitter
(measured jitter-induced error of 2%, Gaussian distribu-
tion, within 3 standard deviations), as a percentage of
the nominal clock frequency.
TABLE 23-3:
TABLE 23-4:
© 2007 Microchip Technology Inc.
40 MHz
24 MHz
16 MHz
Nominal PLL Output
Output
PLL
40 MHz
24 MHz
16 MHz
0.83 ns
1.25 ns
0.5 ns
P
FREQUENCY ERROR FROM JITTER AT VARIOUS PLL GENERATED CLOCK SPEEDS
jitter
TOTAL FREQUENCY ERROR AT VARIOUS PLL GENERATED CLOCK SPEEDS
(100 PPM OSCILLATOR DRIFT, INCLUDING ERROR FROM JITTER)
1.67 ns
2.5 ns
T
(125 Kb/s)
0.01209%
0.01313%
1 ns
0.01125%
jitter
8 μs
Frequency Error at Various Nominal Bit Times (Bit Rates)
PIC18F2682/2685/4682/4685
(125 Kb/s)
0.00125%
0.00209%
0.00313%
8 μs
Frequency Error at Various Nominal Bit Times (Bit Rates)
Preliminary
(250 Kb/s)
0.01250%
0.01418%
0.01625%
4 μs
This is clearly smaller than the expected drift of a crystal
oscillator, typically specified at 100 ppm or 0.01%. If we
add jitter to oscillator drift, we have a total frequency drift
of 0.0132%. The total oscillator frequency errors for
common clock frequencies and bit rates, including both
drift and jitter, are shown in Table 23-4.
(250 Kb/s)
0.00250%
0.00418%
0.00625%
4 μs
(500 Kb/s)
0.015%
0.018%
0.023%
2 μs
(500 Kb/s)
0.005%
0.008%
0.013%
2 μs
DS39761B-page 335
(1 Mb/s)
0.027%
0.035%
0.02%
(1 Mb/s)
1 μs
0.017%
0.025%
0.01%
1 μs