MA180025 Microchip Technology, MA180025 Datasheet - Page 301

• Manufacturer Part Number: MA180025
• Description: MODULE PLUG-IN PIC18F87J90 PIM
• Manufacturer: Microchip Technology
• Series: PIC®r

Specifications of MA180025

• Accessory Type: Plug-In Module (PIM) - PIC18F87J90
• Product: Microcontroller Modules
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18FxxJxx
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: PICDEM LCD 2 Demonstration Board (DM163030)
• For Use With: DM163030 - KIT DEV PICDEM LCD2
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

22.2
A single comparator is shown in Figure 22-2, along with
the relationship between the analog input levels and
the digital output. When the analog input at V
than the analog input, V
comparator is a digital low level. When the analog input
at V
of the comparator is a digital high level. The shaded
areas of the output of the comparator in Figure 22-2
represent the uncertainty due to input offsets and
response time.
22.3
Depending on the comparator operating mode, either
an external or internal voltage reference may be used.
The analog signal present at V
signal at V
is adjusted accordingly (Figure 22-2).
FIGURE 22-2:
22.3.1
When external voltage references are used, the
comparator module can be configured to have the com-
parators operate from the same or different reference
sources. However, threshold detector applications may
require the same reference. The reference signal must
be between V
pin of the comparator(s).
 2010 Microchip Technology Inc.
V
V
Output
IN
IN
IN
-
+
+ is greater than the analog input, V
V
V
IN
IN
Comparator Operation
Comparator Reference
+
-
IN
EXTERNAL REFERENCE SIGNAL
+ and the digital output of the comparator
SS
and V
+
–
SINGLE COMPARATOR
DD
and can be applied to either
IN
-, the output of the
IN
- is compared to the
Output
IN
-, the output
IN
+ is less
PIC18F87J90 FAMILY
22.3.2
The comparator module also allows the selection of an
internally generated voltage reference from the
comparator voltage reference module. This module is
described in more detail in Section 23.0 “Comparator
Voltage Reference Module”.
The internal reference is only available in the mode
where four inputs are multiplexed to two comparators
(CM<2:0> = 110). In this mode, the internal voltage
reference is applied to the V
comparators.
22.4
Response time is the minimum time, after selecting a
new reference voltage or input source, before the
comparator output has a valid level. If the internal ref-
erence is changed, the maximum delay of the internal
voltage reference must be considered when using the
comparator outputs. Otherwise, the maximum delay of
the comparators should be used (see Section 28.0
“Electrical Characteristics”).
22.5
The comparator outputs are read through the CMCON
register. These bits are read-only. The comparator
outputs may also be directly output to the RF1 and RF2
I/O pins. When enabled, multiplexors in the output path
of the RF1 and RF2 pins will switch and the output of
each pin will be the unsynchronized output of the
comparator.
comparators is related to the input offset voltage and
the response time given in the specifications.
Figure 22-3 shows the comparator output block
diagram.
The TRISF bits will still function as an output enable/
disable for the RF1 and RF2 pins while in this mode.
The polarity of the comparator outputs can be changed
using the C2INV and C1INV bits (CMCON<5:4>).
Note 1: When reading the PORT register, all pins
2: Analog levels on any pin defined as a
Comparator Response Time
Comparator Outputs
INTERNAL REFERENCE SIGNAL
configured as analog inputs will read as
‘0’. Pins configured as digital inputs will
convert an analog input according to the
Schmitt Trigger input specification.
digital input may cause the input buffer to
consume more current than is specified.
The
uncertainty
of
DS39933D-page 301
IN
+ pin of both
each
of
the