PIC18F2550-I/SP Microchip Technology Inc., PIC18F2550-I/SP Datasheet - Page 278

• Manufacturer Part Number: PIC18F2550-I/SP
• Description: Microcontroller; 32 KB Flash; 2048 RAM; 256 EEPROM; 24 I/O; 28-Pin-SPDIP
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F2550-I/SP

• A/d Inputs: 10-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 12 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 23
• Interface: I2C/SPI/USART/USB
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 32K Bytes
• Ram Size: 2K Bytes
• Speed: 48 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC18F2455/2550/4455/4550
FIGURE 23-1:
23.2
The full range of voltage reference cannot be realized
due to the construction of the module. The transistors
on the top and bottom of the resistor ladder network
(Figure 23-1) keep CV
ence source rails. The voltage reference is derived
from the reference source; therefore, the CV
changes with fluctuations in that source. The tested
absolute accuracy of the voltage reference can be
found in Section 28.0 “Electrical Characteristics”.
23.3
When the device wakes up from Sleep through an
interrupt or a Watchdog Timer time-out, the contents of
the CVRCON register are not affected. To minimize
current consumption in Sleep mode, the voltage
reference should be disabled.
DS39632C-page 276
Voltage Reference Accuracy/Error
Operation During Sleep
CVRR
V
V
CVREN
V
REF
DD
REF
REF
COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM
+
-
from approaching the refer-
CVRSS = 0
CVRSS = 1
CVRSS = 1
CVRSS = 0
16 Steps
REF
output
Preliminary
8R
R
R
R
R
R
R
R
clearing bit, CVREN (CVRCON<7>). This Reset also
disconnects the reference from the RA2 pin by clearing
23.4
A device Reset disables the voltage reference by
bit, CVROE (CVRCON<6>) and selects the high-voltage
range by clearing bit, CVRR (CVRCON<5>). The CVR
value select bits are also cleared.
23.5
The voltage reference module operates independently
of the comparator module. The output of the reference
generator may be connected to the RA2 pin if the
TRISA<2> bit and the CVROE bit are both set.
Enabling the voltage reference output onto RA2 when
it is configured as a digital input will increase current
consumption. Connecting RA2 as a digital output with
CVRSS
consumption.
The RA2 pin can be used as a simple D/A output with
limited drive capability. Due to the limited current drive
capability, a buffer must be used on the voltage
reference output for external connections to V
Figure 23-2 shows an example buffering technique.
8R
Effects of a Reset
Connection Considerations
enabled
CVR3:CVR0
will
© 2006 Microchip Technology Inc.
also
CV
REF
increase
current
REF
.