PIC16C745/P Microchip Technology, PIC16C745/P Datasheet - Page 93

• Manufacturer Part Number: PIC16C745/P
• Description: 8-Bit CMOS Microcontrollers with USB
• Manufacturer: Microchip Technology

12.2
The A/D conversion time per bit is defined as T
A/D conversion requires 9.5T
The source of the A/D conversion clock is software
selectable. The four possible options for T
For correct A/D conversions, the A/D conversion clock
(T
of 1.6 s.
TABLE 12-1:
12.3
The ADCON1, TRISA and TRISE registers control the
operation of the A/D port pins. The port pins that are
desired as analog inputs must have their corresponding
TRIS bits set (input). If the TRIS bit is cleared (output),
the digital output level (V
The A/D operation is independent of the state of the
CHS<2:0> bits and the TRIS bits.
2T
8T
32T
RC
Note 1: The RC source has a typical T
AD
1999 Microchip Technology Inc.
OSC
OSC
Note 1: When reading the port register, all pins
) must be selected to ensure a minimum T
Operation
OSC
• 2T
• 8T
• 32T
• Dedicated Internal RC oscillator
2: These values violate the minimum required T
3: For faster conversion times, the selection of another clock source is recommended.
4: For device frequencies above 1 MHz, the device must be in SLEEP for the entire conversion, or the A/D
AD Clock Source (T
2: Analog levels on any pin that is defined as
3: The TRISE register is not provided on the
Selecting the A/D Conversion Clock
OSC
OSC
Configuring Analog Port Pins
accuracy may be out of specification.
OSC
configured as analog input channels will
read as cleared (a low level). Pins config-
ured as digital inputs will convert an ana-
log input. Analog levels on a digitally
configured input will not affect the conver-
sion accuracy.
a digital input, but not as an analog input,
may cause the input buffer to consume
current that is out of specification.
PIC16C745.
T
AD
00
01
10
11
ADCS1:ADCS0
vs. DEVICE OPERATING FREQUENCIES
OH
or V
AD
AD
)
OL
per 8-bit conversion.
) will be converted.
AD
100 ns
400 ns
1.6 s
2 - 6 s
AD
time of 4 s.
Advanced Information
are:
20 MHz
AD
(2)
(2)
AD
(1,4)
. The
time
AD
time.
400 ns
1.6 s
6.4 s
2 - 6 s
12.4
Clearing the GO/DONE bit during a conversion will
abort the current conversion. The ADRES register will
NOT be updated with the partially completed A/D con-
version sample. That is, the ADRES register will con-
tinue to contain the value of the last completed
conversion (or the last value written to the ADRES reg-
ister). After the A/D conversion is aborted, a 2T
is required before the next acquisition is started. After
this 2T
the selected channel.
5 MHz
Note:
(2)
(1,4)
Device Frequency
AD
A/D Conversions
wait, an acquisition is automatically started on
The GO/DONE bit should NOT be set in
the same instruction that turns on the A/D.
PIC16C745/765
1.6 s
6.4 s
25.6 s
2 - 6 s
1.25 MHz
(3)
(1,4)
6 s
24 s
96 s
2 - 6 s
DS41124A-page 93
333.33 kHz
(3)
(3)
(1)
AD
wait