PIC18F44J10T-I/ML(2009) View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18F44J10T-I/ML
(Rev.:2009)

28/40/44-Pin High-Performance, RISC Microcontrollers

Microchip Technology 

PIC18F45J10 FAMILY

After the A/D module has been configured as desired,

the selected channel must be acquired before the

conversion is started. The analog input channels must

have their corresponding TRIS bits selected as an

input. To determine acquisition time, see Section 18.1

“A/D Acquisition Requirements”. After this acquisi-

tion time has elapsed, the A/D conversion can be

started. An acquisition time can be programmed to

occur between setting the GO/DONE bit and the actual

start of the conversion.

The following steps should be followed to do an A/D

conversion:

1. Configure the A/D module:

• Configure analog pins, voltage reference and

digital I/O (ADCON1)

• Select A/D input channel (ADCON0)

• Select A/D acquisition time (ADCON2)

• Select A/D conversion clock (ADCON2)

• Turn on A/D module (ADCON0)

2. Configure A/D interrupt (if desired):

• Clear ADIF bit

• Set ADIE bit

• Set GIE bit

3. Wait the required acquisition time (if required).

4. Start conversion:

• Set GO/DONE bit (ADCON0<1>)

5. Wait for A/D conversion to complete, by either:

• Polling for the GO/DONE bit to be cleared

OR

• Waiting for the A/D interrupt

6. Read A/D Result registers (ADRESH:ADRESL);

clear bit, ADIF, if required.

7. For next conversion, go to step 1 or step 2, as

required. The A/D conversion time per bit is

defined as TAD. A minimum wait of 2 TAD is

required before next acquisition starts.

FIGURE 18-2:

ANALOG INPUT MODEL

VDD

RS ANx

VT = 0.6V

RIC ≤ 1k

Sampling

Switch

SS RSS

VAIN

CPIN

5 pF

VT = 0.6V

ILEAKAGE

±100 nA

CHOLD = 25 pF

VSS

Legend: CPIN

VT

ILEAKAGE

RIC

SS

CHOLD

RSS

= Input Capacitance

= Threshold Voltage

= Leakage Current at the pin due to

various junctions

= Interconnect Resistance

= Sampling Switch

= Sample/Hold Capacitance (from DAC)

= Sampling Switch Resistance

VDD

1 23 4

Sampling Switch (kΩ)

© 2009 Microchip Technology Inc.

DS39682E-page 219

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