PIC12F1822 MICROCHIP [Microchip Technology], PIC12F1822 Datasheet - Page 164

• Manufacturer Part Number: PIC12F1822
• Description: 8/14-Pin Flash Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC12F/LF1822/16F/LF1823
18.7
The CxNCH<1:0> bits of the CMxCON0 register direct
one of the analog pins to the comparator inverting
input.
18.8
The comparator output is indeterminate for a period of
time after the change of an input source or the selection
of a new reference voltage. This period is referred to as
the response time. The response time of the comparator
differs from the settling time of the voltage reference.
Therefore, both of these times must be considered when
determining the total response time to a comparator
input change. See the Comparator and Voltage Refer-
ence Specifications in Section 29.0 “Electrical Specifi-
cations” for more details.
18.9
The C1 and C2 comparators can be used as general
purpose comparators. Their outputs can be brought
out to the C1OUT and C2OUT pins. When the ECCP
Auto-Shutdown is active it can use one or both
comparators. If auto-restart is also enabled, the
comparators can be configured as a closed loop
analog feedback to the ECCP, thereby, creating an
analog controlled PWM.
FIGURE 18-4:
DS41413A-page 164
Note:
Comparator Negative Input
Selection
Comparator Response Time
Interaction with ECCP Logic
Legend: C
V
To use CxIN+ and CxINx- pins as analog
input, the appropriate bits must be set in
the ANSEL register and the corresponding
TRIS bits must also be set to disable the
output drivers.
A
Note 1: See Section 29.0 “Electrical Specifications”.
Rs < 10K
I
R
R
V
V
ANALOG INPUT MODEL
LEAKAGE
A
T
PIN
IC
S
Analog
Input
pin
= Input Capacitance
= Leakage Current at the pin due to various junctions
= Interconnect Resistance
= Source Impedance
= Analog Voltage
= Threshold Voltage
C
5 pF
PIN
V
DD
V
V
Preliminary
T
T
 0.6V
 0.6V
18.10 Analog Input Connection
A simplified circuit for an analog input is shown in
Figure 18-4. Since the analog input pins share their
connection with a digital input, they have reverse
biased ESD protection diodes to V
analog input, therefore, must be between V
If the input voltage deviates from this range by more
than 0.6V in either direction, one of the diodes is for-
ward biased and a latch-up may occur.
A maximum source impedance of 10 k is recommended
for the analog sources. Also, any external component
connected to an analog input pin, such as a capacitor or
a Zener diode, should have very little leakage current to
minimize inaccuracies introduced.
Note 1: When reading a PORT register, all pins
I
Vss
LEAKAGE
2: Analog levels on any pin defined as a
Considerations
configured as analog inputs will read as a
‘0’. Pins configured as digital inputs will
convert as an analog input, according to
the input specification.
digital input, may cause the input buffer to
consume more current than is specified.
R
IC
(1)
 2010 Microchip Technology Inc.
To Comparator
DD
and V
SS
and V
SS
. The
DD
.