PIC18F97J60 Datasheet, PDF (341/474 Pages) Microchip Technology – 64/80/100-Pin, High-Performance, 1 Mbit Flash Microcontrollers with Ethernet

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22.9 Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 22-4. Since the analog pins are connected to a
digital output, they have reverse biased 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 condition may
occur. A maximum source impedance of 10 kΩ is
recommended for the analog sources. Any external
component connected to an analog input pin, such as
a capacitor or a Zener diode, should have very little
leakage current.
FIGURE 22-4:
COMPARATOR ANALOG INPUT MODEL
VDD
RS < 10k
VT = 0.6V
RIC
AIN
VA
CPIN
5 pF
VT = 0.6V
ILEAKAGE
±500 nA
Comparator
Input
VSS
Legend:
CPIN
=
VT
=
ILEAKAGE =
RIC
=
RS
=
VA
=
Input Capacitance
Threshold Voltage
Leakage Current at the pin due to various junctions
Interconnect Resistance
Source Impedance
Analog Voltage
TABLE 22-1: REGISTERS ASSOCIATED WITH COMPARATOR MODULE
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF
59
PIR2
OSCFIF
CMIF
ETHIF
r
BCL1IF
—
TMR3IF CCP2IF
61
PIE2
OSCFIE CMIE ETHIE
r
BCL1IE
—
TMR3IE CCP2IE 61
IPR2
OSCFIP CMIP ETHIP
r
BCL1IP
—
TMR3IP CCP2IP 61
CMCON
C2OUT C1OUT C2INV C1INV
CIS
CM2
CM1
CM0
60
CVRCON CVREN CVROE CVRR CVRSS CVR3 CVR2 CVR1 CVR0
60
PORTF
RF7
RF6
RF5
RF4
RF3
RF2
RF1
RF0
62
TRISF
TRISF7 TRISF6 TRISF5 TRISF4 TRISF3 TRISF2 TRISF1 TRISF0
61
Legend: — = unimplemented, read as ‘0’, r = reserved. Shaded cells are unused by the comparator module.
© 2006 Microchip Technology Inc.
Advance Information
DS39762A-page 339