PIC16F193X Datasheet, PDF (149/418 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt Technology

PIC16F193X/LF193X
12.8 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 Refer-
ence Specifications in Section 28.0 “Electrical Specifi-
cations” for more details.
12.9 Interaction with ECCP Logic
The C1 and C2 comparators can be used as general
purpose comparators. Their outputs can be brought
out to the C1OUT and C2OUT pins. However, 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.
12.10 Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 12-3. 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 for-
ward biased and a latch-up may occur.
A maximum source impedance of 10 kΩ 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.
FIGURE 12-3:
ANALOG INPUT MODEL
VDD
Rs < 10K
VA
AIN
CPIN
5 pF
VT ≈ 0.6V
VT ≈ 0.6V
RIC
ILEAKAGE⁽¹⁾
To Comparator
Vss
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 28.0 “Electrical Specifications”
© 2008 Microchip Technology Inc.
Preliminary
DS41364A-page 147