PIC18F4431-E/ML Microchip Technology, PIC18F4431-E/ML Datasheet - Page 26

• Manufacturer Part Number: PIC18F4431-E/ML
• Description: IC MCU FLASH 8KX16 44QFN
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F4431-E/ML

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, Power Control PWM, QEI, POR, PWM, WDT
• Number Of I /o: 36
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 9x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 44-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PIC18F2331/2431/4331/4431
2.2
2.2.1
The use of decoupling capacitors on every pair of
power supply pins, such as V
AV
Consider the following criteria when using decoupling
capacitors:
• Value and type of capacitor: A 0.1 F (100 nF),
• Placement on the printed circuit board: The
• Handling high-frequency noise: If the board is
• Maximizing performance: On the board layout
DS39616D-page 26
10-20V capacitor is recommended. The capacitor
should be a low-ESR device, with a resonance
frequency in the range of 200 MHz and higher.
Ceramic capacitors are recommended.
decoupling capacitors should be placed as close
to the pins as possible. It is recommended to
place the capacitors on the same side of the
board as the device. If space is constricted, the
capacitor can be placed on another layer on the
PCB using a via; however, ensure that the trace
length from the pin to the capacitor is no greater
than 0.25 inch (6 mm).
experiencing high-frequency noise (upward of
tens of MHz), add a second ceramic type capaci-
tor in parallel to the above described decoupling
capacitor. The value of the second capacitor can
be in the range of 0.01 F to 0.001 F. Place this
second capacitor next to each primary decoupling
capacitor. In high-speed circuit designs, consider
implementing a decade pair of capacitances as
close to the power and ground pins as possible
(e.g., 0.1 F in parallel with 0.001 F).
from the power supply circuit, run the power and
return traces to the decoupling capacitors first,
and then to the device pins. This ensures that the
decoupling capacitors are first in the power chain.
Equally important is to keep the trace length
between the capacitor and the power pins to a
minimum, thereby reducing PCB trace
inductance.
SS
, is required.
Power Supply Pins
DECOUPLING CAPACITORS
DD
, V
SS
, AV
DD
and
2.2.2
On boards with power traces running longer than
six inches in length, it is suggested to use a tank capac-
itor for integrated circuits, including microcontrollers, to
supply a local power source. The value of the tank
capacitor should be determined based on the trace
resistance that connects the power supply source to
the device, and the maximum current drawn by the
device in the application. In other words, select the tank
capacitor so that it meets the acceptable voltage sag at
the device. Typical values range from 4.7 F to 47 F.
2.2.3
When the Brown-out Reset (BOR) feature is enabled,
a sudden change in V
BOR event. This can happen when the microcontroller
is operating under normal operating conditions, regard-
less of what the BOR set point has been programmed
to, and even if V
The precipitating factor in these BOR events is a rise or
fall in V
An application that incorporates adequate decoupling
between the power supplies will not experience such
rapid voltage changes. Additionally, the use of an
electrolytic tank capacitor across V
described above, will be helpful in preventing high slew
rate transitions.
If the application has components that turn on or off,
and share the same V
the BOR can be disabled in software by using the
SBOREN bit before switching the component. After-
wards, allow a small delay before re-enabling the BOR.
By doing this, it is ensured that the BOR is disabled
during the interval that might cause high slew rate
changes of V
Note:
DD
with a slew rate faster than 0.15V/s.
TANK CAPACITORS
CONSIDERATIONS WHEN USING
BOR
Not all devices incorporate software BOR
control. See
device-specific information.
DD
.
DD
does not approach the set point.
DD
DD
 2010 Microchip Technology Inc.
may result in a spontaneous
circuit as the microcontroller,
Section 5.0 “Reset”
DD
and V
SS
, as
for