PIC18C242/JW Microchip Technology, PIC18C242/JW Datasheet - Page 27

• Manufacturer Part Number: PIC18C242/JW
• Description: IC MCU EPROM 8KX16 A/D 28CDIP
• Manufacturer: Microchip Technology
• Series: PIC® 18Cr

Specifications of PIC18C242/JW

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: EPROM, UV
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 28-CDIP (0.300", 7.62mm) Window
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

3.0
The PIC18CXX2 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:
2001 Microchip Technology Inc.
Note 1: This is a separate oscillator from the RC oscillator of the CLKIN 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
MCLR
OSC1
Instruction
V
DD
RESET
2: See Table 3-1 for time-out situations.
RESET
Pointer
Stack
OST/PWRT
RC OSC
On-chip
Brown-out
V
Module
Detect
DD
WDT
Reset
(1)
Rise
Stack Full/Underflow Reset
External Reset
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
PWRT
OST
Time-out
Reset
WDT
10-bit Ripple Counter
10-bit Ripple Counter
BOREN
Power-on Reset
SLEEP
Enable PWRT
Enable OST
(2)
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.
MCLR pin is not driven low by any internal RESETS,
including WDT.
PIC18CXX2
S
R
Q
DS39026C-page 25
Chip_Reset