PIC18LF24K Datasheet, PDF (428/594 Pages) –

PIC18(L)F26/45/46K40
TABLE 31-1: ADC CLOCK PERIOD (TAD) VS. DEVICE OPERATING FREQUENCIES^(1,4)
ADC Clock Period (TAD)
Device Frequency (FOSC)
ADC
Clock Source
ADCS<5:0>
64 MHz
32 MHz
20 MHz 16 MHz
8 MHz
4 MHz
1 MHz
FOSC/2
FOSC/4
FOSC/6
FOSC/8
000000
000001
000010
000011
31.25 ns⁽²⁾
62.5 ns⁽²⁾
125 ns⁽²⁾
187.5 ns⁽²⁾
62.5 ns⁽²⁾
125 ns⁽²⁾
187.5 ns⁽²⁾
250 ns⁽²⁾
100 ns⁽²⁾
200 ns⁽²⁾
300 ns⁽²⁾
400 ns⁽²⁾
125 ns⁽²⁾
250 ns⁽²⁾
375 ns⁽²⁾
500 ns⁽²⁾
250 ns⁽²⁾
500 ns⁽²⁾
750 ns⁽²⁾
1.0 s
500 ns⁽²⁾
1.0 s
1.5 s
2.0 s
2.0 s
4.0 s
6.0 s
8.0 s⁽³⁾
...
FOSC/16
...
000100
...
250 ns⁽²⁾
...
500 ns⁽²⁾
...
800 ns⁽²⁾
...
1.0 s
...
2.0 s
...
4.0 s
...
16.0 s⁽³⁾
...
FOSC/128
FRC
Legend:
Note 1:
2:
3:
4:
...
111111
...
2.0 s
...
4.0 s
...
6.4 s
...
8.0 s
...
16.0 s⁽³⁾
...
...
32.0 s⁽²⁾ 128.0 s⁽²⁾
ADCS(ADCON0<4>) = 1 1.0-6.0 s 1.0-6.0 s 1.0-6.0 s 1.0-6.0 s 1.0-6.0 s 1.0-6.0 s 1.0-6.0 s
Shaded cells are outside of recommended range.
See TAD parameter for FRC source typical TAD value.
These values violate the required TAD time.
Outside the recommended TAD time.
The ADC clock period (TAD) and total ADC conversion time can be minimized when the ADC clock is derived from the system
clock FOSC. However, the FRC oscillator source must be used when conversions are to be performed with the device in Sleep
mode.
FIGURE 31-2:
ANALOG-TO-DIGITAL CONVERSION TAD CYCLES
Precharge
Time
1-127 TCY
(TPRE)
Acquisition/
Sharing Time
1-127 TCY
(TACQ)
Conversion Time
(Traditional Timing of ADC Conversion)
Rev. 10-000035B
7/15/2016
TCY TCY-TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 _TAD8 TAD9 TAD10TAD11 2 TCY
b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
External and Internal External and Internal
Channels are
Channels share
charged/discharged charge
Conversion starts
Holding capacitor CHOLD is disconnected from analog input (typically 100ns)
If ADPRE  0
Set GO bit
If ADACQ  0
If ADPRE = 0
If ADACQ = 0
(Traditional Operation Start)
On the following cycle:
ADRESH:ADRESL is loaded,
GO bit is cleared,
ADIF bit is set,
 2016 Microchip Technology Inc.
Preliminary
DS40001816C-page 428