41594B datasheet(127/372 Pages) MICROCHIP

127 / 372 page

 2011-2012 Microchip Technology Inc.

Preliminary

DS41594B-page 127

PIC12LF1840T48A

TABLE 16-1:

ADC CLOCK PERIOD (TAD) VS. DEVICE OPERATING FREQUENCIES

FIGURE 16-2:

ANALOG-TO-DIGITAL CONVERSION TAD CYCLES

ADC Clock Period (TAD)

Device Frequency (FOSC)

ADC

Clock Source

ADCS<2:0>

32 MHz

20 MHz

16 MHz

8 MHz

4 MHz

1 MHz

Fosc/2

000

62.5ns(2)

100 ns(2)

125 ns(2)

250 ns(2)

500 ns(2)

2.0

s

Fosc/4

100

125 ns(2)

200 ns(2)

250 ns(2)

500 ns(2)

1.0

s4.0 s

Fosc/8

001

0.5

s(2)

400 ns(2)

0.5

s(2)

1.0

s2.0 s

8.0

s(3)

Fosc/16

101

800 ns

1.0

s2.0 s4.0 s

16.0

s(3)

Fosc/32

010

1.0

s1.6 s2.0 s4.0 s

8.0

s(3)

32.0

s(3)

Fosc/64

110

2.0

s3.2 s4.0 s

8.0

s(3)

16.0

s(3)

64.0

s(3)

FRC

x11

1.0-6.0

s(1,4)

1.0-6.0

s(1,4)

1.0-6.0

s(1,4)

1.0-6.0

s(1,4)

1.0-6.0

s(1,4)

1.0-6.0

s(1,4)

Legend:

Shaded cells are outside of recommended range.

Note 1:

The FRC source has a typical TAD time of 1.6

s for VDD.

These values violate the minimum required TAD time.

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

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 clock source must be used when conversions are to be performed with the

device in Sleep mode.

TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8

TAD11

Set GO bit

Holding capacitor is disconnected from analog input (typically 100 ns)

TAD9 TAD10

TCY - TAD

ADRESH:ADRESL is loaded, GO bit is cleared,

ADIF bit is set, holding capacitor is connected to analog input.

Conversion starts

On the following cycle:

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