PIC18F452-E/PT Microchip Technology, PIC18F452-E/PT Datasheet - Page 27

• Manufacturer Part Number: PIC18F452-E/PT
• Description: IC MCU CMOS 40MHZ 16K FLSH44TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F452-E/PT

• Core Size: 8-Bit
• Program Memory Size: 32KB (16K x 16)
• Core Processor: PIC
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 34
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 1.5K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 44-TQFP, 44-VQFP
• Controller Family/series: PIC18
• No. Of I/o's: 34
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 1.5KB
• Cpu Speed: 40MHz
• No. Of Timers: 4
• Package: 44TQFP
• Device Core: PIC
• Family Name: PIC18
• Maximum Speed: 40 MHz
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 34
• Interface Type: I2C/SPI/USART
• On-chip Adc: 8-chx10-bit
• Number Of Timers: 4
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3.0
The PIC18FXXX differentiates between various kinds
of RESET:
a)
b)
c)
d)
e)
f)
g)
h)
Most registers are unaffected by a RESET. Their status
is unknown on POR and unchanged by all other
RESETS. The other registers are forced to a “RESET
state” on Power-on Reset, MCLR, WDT Reset, Brown-
out Reset, MCLR Reset during SLEEP and by the
RESET instruction.
FIGURE 3-1:
© 2006 Microchip Technology Inc.
MCLR
OSC1
V
Note 1: This is a separate oscillator from the RC oscillator of the CLKI pin.
Power-on Reset (POR)
MCLR Reset during normal operation
MCLR Reset during SLEEP
Watchdog Timer (WDT) Reset (during normal
operation)
Programmable Brown-out Reset (BOR)
RESET Instruction
Stack Full Reset
Stack Underflow Reset
DD
Instruction
RESET
RESET
2: See Table 3-1 for time-out situations.
Pointer
RC OSC
Stack
On-chip
OST/PWRT
Brown-out
V
Module
Detect
(1)
DD
WDT
Reset
Rise
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
Stack Full/Underflow Reset
OST
PWRT
External Reset
10-bit Ripple Counter
Time-out
Reset
10-bit Ripple Counter
WDT
BOREN
Power-on Reset
SLEEP
Enable PWRT
Enable OST
Most registers are not affected by a WDT wake-up,
since this is viewed as the resumption of normal oper-
ation. Status bits from the RCON register, RI, TO, PD,
POR and BOR, are set or cleared differently in different
RESET situations, as indicated in Table 3-2. These bits
are used in software to determine the nature of the
RESET. See Table 3-3 for a full description of the
RESET states of all registers.
A simplified block diagram of the On-Chip Reset Circuit
is shown in Figure 3-1.
The Enhanced MCU devices have a MCLR noise filter
in the MCLR Reset path. The filter will detect and
ignore small pulses.
The MCLR pin is not driven low by any internal
RESETS, including the WDT.
(2)
PIC18FXX2
S
R
DS39564C-page 25
Q
Chip_Reset