Datasheet

PIC18F85J90 FAMILY
DS39770C-page 402  2010 Microchip Technology Inc.
B.4 Pin Differences
Besides the LCD pinout differences already described,
there are other differences in the pinouts between the
PIC18F85J90 and the PIC18F8490 families:
• Input voltage tolerance
• Output current capabilities
• Available I/O
Pins on the PIC18F85J90 that have digital only input
capability will tolerate voltages up to 5.5V, and are thus,
tolerant to voltages above V
DD. Table 10-1 in
Section 10.1 “I/O Port Pin Capabilities” contains the
complete list.
In addition to input differences, there are output differ-
ences as well. PIC18F85J90 devices have three
classes of pin output current capability: high, medium
and low. Not all I/O pins can source or sink equal levels
of current. Only PORTB and PORTC support the
25 mA source/sink capability that is supported by all
output pins on the PIC18F8490. Table 10-1 in
Section 10.1 “I/O Port Pin Capabilities” contains the
complete list of output capabilities.
Finally, the pins associated with the CCP,
EUSART/AUSART and SPI peripherals can be config-
ured by the user as open-drain outputs. This allows for
simpler interfacing with external devices operating at
higher voltages. This capability is not directly
equivalent to any feature on the PIC18F8490 family.
There are also differences in the implementation of
some ports on PIC18F85J90 devices. While the total
number of general purpose I/O pins are very similar
(67 vs. 66), the implementation of individual pins has
notable differences:
•The MCLR
pin is dedicated only to MCLR and
cannot be configured as an input (RG5) as it can
on PIC18F8490 devices.
• RF0 does not exist on PIC18F85J90 devices.
• RE0, RE1 and RE3 are implemented on
PIC18F85J90 devices, but not PIC18F8490
devices.
All of these pin differences (including power pin
differences) should be accounted for when making a
conversion between PIC18F8490 and PIC18F85J90
devices.
B.5 Other Peripherals
Peripherals must also be considered when making a
conversion between the PIC18F85J90 and the
PIC18F8490 families:
• A/D Converter: The converter for PIC18F85J90
devices require a calibration step prior to normal
operation.
• Data EEPROM: PIC18F85J90 devices do not
have this module but offer self-programming
capability.
• BOR: PIC18F85J90 devices do not have a
programmable BOR. Simple brown-out capability
is provided through the use of the internal voltage
regulator.
• LVD: PIC18F85J90 devices do not have this
module. A limited, fixed setpoint capability is
provided through the use of the internal voltage
regulator.