PIC18F23K22-ESLASHML datasheet(293/496 Pages) MICROCHIP

293 / 496 page

 2010 Microchip Technology Inc.

Preliminary

DS41412C-page 293

PIC18(L)F2X/4XK22

17.1.5

CONVERSION CLOCK

The source of the conversion clock is software

selectable via the ADCS bits of the ADCON2 register.

There are seven possible clock options:

•FOSC/2

•FOSC/4

•FOSC/8

•FOSC/16

•FOSC/32

•FOSC/64

•FRC (dedicated internal oscillator)

The time to complete one bit conversion is defined as

TAD. One full 10-bit conversion requires 11 TAD periods

as shown in Figure 17-3.

For correct conversion, the appropriate TAD specification

must be met. See A/D conversion requirements in

Table 27-24 for more information. Table gives examples

of appropriate ADC clock selections.

17.1.6

INTERRUPTS

The ADC module allows for the ability to generate an

interrupt upon completion of an Analog-to-Digital

Conversion. The ADC interrupt enable is the ADIE bit

in the PIE1 register and the interrupt priority is the ADIP

bit in the IPR1 register. The ADC interrupt flag is the

ADIF bit in the PIR1 register. The ADIF bit must be

cleared by software.

This interrupt can be generated while the device is

operating or while in Sleep. If the device is in Sleep, the

interrupt will wake-up the device. Upon waking from

Sleep, the next instruction following the SLEEP

instruction is always executed. If the user is attempting

to wake-up from Sleep and resume in-line code

execution, the global interrupt must be disabled. If the

global interrupt is enabled, execution will switch to the

Interrupt Service Routine.

Note:

Unless using the FRC, any changes in the

system clock frequency will change the

ADC

clock

frequency,

which

may

adversely affect the ADC result.

Note:

The ADIF bit is set at the completion of

every conversion, regardless of whether

or not the ADC interrupt is enabled.

TABLE 17-1:

ADC CLOCK PERIOD (TAD) VS. DEVICE OPERATING FREQUENCIES

ADC Clock Period (TAD)

Device Frequency (FOSC)

ADC Clock Source

ADCS<2:0>

64 MHz

16 MHz

4 MHz

1 MHz

FOSC/2

000

31.25 ns(2)

125 ns(2)

500 ns(2)

2.0

s

FOSC/4

100

62.5 ns(2)

250 ns(2)

1.0

s

4.0

s(3)

FOSC/8

001

400 ns(2)

500 ns(2)

2.0

s

8.0

s(3)

FOSC/16

101

250 ns(2)

1.0

s

4.0

s(3)

16.0

s(3)

FOSC/32

010

500 ns(2)

2.0

s

8.0

s(3)

32.0

s(3)

FOSC/64

110

1.0

s

4.0

s(3)

16.0

s(3)

64.0

s(3)

FRC

x11

1-4

s(1,4)

1-4

s(1,4)

1-4

s(1,4)

1-4

s(1,4)

Legend: Shaded cells are outside of recommended range.

Note 1:

The FRC source has a typical TAD time of 1.7

s.

These values violate the minimum required TAD time.

For faster conversion times, the selection of another clock source is recommended.

When the device frequency is greater than 1 MHz, the FRC clock source is only recommended if the

conversion will be performed during Sleep.

PIC18F23K22-E/ML Datasheet(PDF) 293 Page - Microchip Technology

PIC18F23K22-E/ML Datasheet(HTML) 293 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL