PIC18F87J72-I/PT Microchip Technology, PIC18F87J72-I/PT Datasheet - Page 295

• Manufacturer Part Number: PIC18F87J72-I/PT
• Description: IC PIC MCU 8BIT 14KB FLSH 80TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F87J72-I/PT

• Program Memory Type: FLASH
• Program Memory Size: 128KB (64K x 16)
• Package / Case: 80-TQFP
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 48MHz
• Connectivity: I²C, LIN, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LCD, LVD, POR, PWM, WDT
• Number Of I /o: 51
• Ram Size: 3.8K x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 3.6 V
• Data Converters: A/D 12x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: SPI, USART, SPI, I2C
• Maximum Clock Frequency: 8 MHz
• Number Of Programmable I/os: 51
• Number Of Timers: 4
• Operating Supply Voltage: 2 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 14
• Controller Family/series: PIC18F
• No. Of I/o's: 51
• Ram Memory Size: 3923Byte
• Cpu Speed: 48MHz
• No. Of Timers: 4
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

23.2
A single comparator is shown in Figure 23-2, along with
the relationship between the analog input levels and
the digital output. When the analog input at V
than the analog input V
is a digital low level. When the analog input at V
greater than the analog input V
comparator is a digital high level. The shaded areas of
the output of the comparator in Figure 23-2 represent
the uncertainty due to input offsets and response time.
23.3
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 23-2).
FIGURE 23-2:
23.3.1
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
-
+
V
V
IN
IN
Comparator Operation
Comparator Reference
+
-
IN
EXTERNAL REFERENCE SIGNAL
+ and the digital output of the comparator
SS
and V
+
–
IN
SINGLE COMPARATOR
DD
-, the output of the comparator
and can be applied to either
IN
IN
- is compared to the
-, the output of the
Output
IN
+ is less
IN
+ is
Preliminary
PIC18F87J72 FAMILY
23.3.2
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 24.0 “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
23.4
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 29.0
“Electrical Characteristics”).
23.5
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, multiplexers 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 23-3 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
IN
+ pin of both comparators.
of
DS39979A-page 295
each
of
the