PIC18LF24K Datasheet, PDF (468/594 Pages) –

PIC18(L)F26/45/46K40
32.9 Comparator Response Time
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
Reference Specifications in Table 37-15 and Table 37-
17 for more details.
FIGURE 32-3:
ANALOG INPUT MODEL
32.10 Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 32-3. Since the analog input pins share their
connection with a digital input, they have reverse
biased ESD protection diodes to VDD and VSS. The
analog input, therefore, must be between VSS and VDD.
If the input voltage deviates from this range by more
than 0.6V in either direction, one of the diodes is
forward 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
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.
2: Analog levels on any pin defined as a
digital input, may cause the input buffer to
consume more current than is specified.
Analog
RS < 10K ^{Input pin}
VA
CPIN
5pF
VDD
VT § 0.6V
VT § 0.6V
RIC
ILEAKAGE⁽¹⁾
VSS
Rev. 10-000071A
8/2/2013
To Comparator
Legend: CPIN = Input Capacitance
ILEAKAGE = Leakage Current at the pin due to various junctions
RIC
= Interconnect Resistance
RS
= Source Impedance
VA
= Analog Voltage
VT
= Threshold Voltage
Note 1: See Section 37.0 “Electrical Specifications”.
 2016 Microchip Technology Inc.
Preliminary
DS40001816C-page 468