PIC18F2221-E/SS Microchip Technology, PIC18F2221-E/SS Datasheet - Page 49

• Manufacturer Part Number: PIC18F2221-E/SS
• Description: 4KB, Flash, 512bytes-RAM, 25I/O, 8-bit Family,nanoWatt 28 SSOP .209in TUBE
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F2221-E/SS

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 25
• Program Memory Size: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 10x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 28-SSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

5.2
The MCLR pin provides a method for triggering an
external Reset of the device. A Reset is generated by
holding the pin low. These devices have a noise filter in
the MCLR Reset path which detects and ignores small
pulses.
The MCLR pin is not driven low by any internal Resets,
including the WDT.
In PIC18F2221/2321/4221/4321 family devices, the
MCLR input can be disabled with the MCLRE Configu-
ration bit. When MCLR is disabled, the pin becomes a
digital input. See Section 11.5 “PORTE, TRISE and
LATE Registers” for more information.
5.3
A Power-on Reset pulse is generated on-chip
whenever V
allows the device to start in the initialized state when
V
To take advantage of the POR circuitry, tie the MCLR
pin through a resistor (1 kΩ to 10 kΩ) to V
eliminate external RC components usually needed to
create a Power-on Reset delay. A minimum rise rate for
V
time, see Figure 5-2.
When the device starts normal operation (i.e., exits the
Reset
(voltage, frequency, temperature, etc.) must be met to
ensure operation. If these conditions are not met, the
device must be held in Reset until the operating
conditions are met.
Power-on Reset events are captured by the POR bit
(RCON<1>). The state of the bit is set to ‘0’ whenever
a POR occurs; it does not change for any other Reset
event. POR is not reset to ‘1’ by any hardware event.
To capture multiple events, the user manually resets
the bit to ‘1’ in software following any POR.
© 2009 Microchip Technology Inc.
DD
DD
is adequate for operation.
is specified (parameter D004). For a slow rise
condition),
Master Clear (MCLR)
Power-on Reset (POR)
DD
rises above a certain threshold. This
device
PIC18F2221/2321/4221/4321 FAMILY
operating
DD
parameters
. This will
FIGURE 5-2:
Note 1: External Power-on Reset circuit is required
V
2: R < 40 kΩ is recommended to make sure that
3: R1 ≥ 1 kΩ will limit any current flowing into
DD
D
only if the V
The diode D helps discharge the capacitor
quickly when V
the voltage drop across R does not violate
the device’s electrical specification.
MCLR from external capacitor C, in the event
of MCLR/V
Electrostatic Discharge (ESD) or Electrical
Overstress (EOS).
V
DD
R
C
EXTERNAL POWER-ON
RESET CIRCUIT (FOR
SLOW V
DD
PP
DD
R1
power-up slope is too slow.
pin breakdown, due to
powers down.
DD
PIC18FXXXX
MCLR
POWER-UP)
DS39689F-page 49