PIC18F25J50 MICROCHIP [Microchip Technology], PIC18F25J50 Datasheet - Page 387

• Manufacturer Part Number: PIC18F25J50
• Description: 28/44-Pin, Low-Power, High-Performance USB Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

23.2
A single comparator is shown in
the relationship between the analog input levels and
the digital output. When the analog input at V
than the analog input, V
tor is a digital low level. When the analog input at V
is greater than the analog input, V
comparator is a digital high level. The shaded areas of
the output of the comparator in
the uncertainty due to input offsets and response time.
FIGURE 23-2:
FIGURE 23-3:
 2011 Microchip Technology Inc.
V
V
Output
IN
IN
-
+
V
V
IN
IN
Comparator Operation
+
-
VA
R
S
Legend:
+
–
< 10k
SINGLE COMPARATOR
COMPARATOR ANALOG INPUT MODEL
IN
-, the output of the compara-
A
IN
Figure
C
V
I
R
R
VA
Figure 23-2
LEAKAGE
C
5 pF
T
PIN
IC
S
IN
PIN
-, the output of the
23-2, along with
Output
= Input Capacitance
= Threshold Voltage
= Leakage Current at the pin due to various junctions
= Interconnect Resistance
= Source Impedance
= Analog Voltage
IN
represent
+ is less
IN
V
+
DD
V
V
T
T
= 0.6V
= 0.6V
PIC18F46J50 FAMILY
23.3
Response time is the minimum time, after selecting a
new reference voltage or input source, before the
comparator output has a valid level. 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 to
a comparator input change. Otherwise, the maximum
delay of the comparators should be used (see
Section 30.0 “Electrical
23.4
Figure 23-3
input. Since the analog pins are connected to a digital
output, they have reverse biased diodes to V
The analog input, therefore, must be between V
V
more than 0.6V in either direction, one of the diodes is
forward biased and a latch-up condition may occur. A
maximum source impedance of 10 k is recommended
for the analog sources. Any external component con-
nected to an analog input pin, such as a capacitor or a
Zener diode, should have very little leakage current.
DD
. If the input voltage deviates from this range by
Comparator
Analog Input Connection
Considerations
I
±100 nA
V
LEAKAGE
SS
provides a simplified circuit for an analog
R
IC
Response Time
Characteristics”).
Comparator
Input
DS39931D-page 387
DD
and V
SS
and
SS
.