Datasheet
PIC16F630/676
DS40039F-page 46 2010 Microchip Technology Inc.
TABLE 7-1: TAD vs. DEVICE OPERATING FREQUENCIES
7.1.5 STARTING A CONVERSION
The A/D conversion is initiated by setting the
GO/DONE
bit (ADCON0<1>). When the conversion is
complete, the A/D module:
• Clears the GO/DONE bit
• Sets the ADIF flag (PIR1<6>)
• Generates an interrupt (if enabled)
If the conversion must be aborted, the GO/DONE bit
can be cleared in software. The ADRESH:ADRESL
registers will not be updated with the partially complete
A/D conversion sample. Instead, the
ADRESH:ADRESL registers will retain the value of the
previous conversion. After an aborted conversion, a
2T
AD delay is required before another acquisition can
be initiated. Following the delay, an input acquisition is
automatically started on the selected channel.
7.1.6 CONVERSION OUTPUT
The A/D conversion can be supplied in two formats: left
or right shifted. The ADFM bit (ADCON0<7>) controls
the output format. Figure 7-2 shows the output formats.
FIGURE 7-2: 10-BIT A/D RESULT FORMAT
A/D Clock Source (TAD) Device Frequency
Operation ADCS2:ADCS0 20 MHz 5 MHz 4 MHz 1.25 MHz
2 TOSC 000 100 ns
(2)
400 ns
(2)
500 ns
(2)
1.6 s
4 TOSC 100 200 ns
(2)
800 ns
(2)
1.0 s
(2)
3.2 s
8 TOSC 001 400 ns
(2)
1.6 s2.0 s6.4 s
16 T
OSC 101 800 ns
(2)
3.2 s4.0 s 12.8 s
(3)
32 TOSC 010 1.6 s6.4 s 8.0 s
(3)
25.6 s
(3)
64 TOSC 110 3.2 s 12.8 s
(3)
16.0 s
(3)
51.2 s
(3)
A/D RC x11 2 - 6 s
(1,4)
2 - 6 s
(1,4)
2 - 6 s
(1,4)
2 - 6 s
(1,4)
Legend:Shaded cells are outside of recommended range.
Note 1: The A/D RC source has a typical T
AD time of 4 s for VDD > 3.0V.
2: These values violate the minimum required T
AD time.
3: For faster conversion times, the selection of another clock source is recommended.
4: When the device frequency is greater than 1 MHz, the A/D RC clock source is only recommended if the
conversion will be performed during Sleep.
Note: The GO/DONE bit should not be set in the
same instruction that turns on the A/D.
ADRESH ADRESL
(ADFM = 0)MSB LSB
bit 7bit 0bit 7bit 0
10-bit A/D Result Unimplemented: Read as ‘0’
(ADFM = 1)
MSB LSB
bit 7bit 0bit 7bit 0
Unimplemented: Read as ‘0’ 10-bit A/D Result