PIC16LC63A-04 Datasheet, PDF (88/184 Pages) Microchip Technology – 8-Bit CMOS Microcontrollers with A/D Converter

PIC16C63A/65B/73B/74B
13.3 RESET
The PIC16CXX differentiates between various kinds of
RESET:
• Power-on Reset (POR)
• MCLR Reset during normal operation
• MCLR Reset during SLEEP
• WDT Reset (normal operation)
• Brown-out Reset (BOR)
Some registers are not affected in any RESET condi-
tion; their status is unknown on POR and unchanged in
any other RESET. Most other registers are reset to a
“RESET state” on POR, on the MCLR and WDT Reset,
on MCLR Reset during SLEEP, and on BOR. The TO
and PD bits are set or cleared differently in different
RESET situations, as indicated in Table 13-4. These
bits are used in software to determine the nature of the
RESET. See Table 13-6 for a full description of RESET
states of all registers.
A simplified block diagram of the on-chip RESET circuit
is shown in Figure 13-4.
The PICmicro devices have a MCLR noise filter in the
MCLR Reset path. The filter will detect and ignore
small pulses.
It should be noted that internal RESET sources do not
drive MCLR pin low.
FIGURE 13-4:
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
External
RESET
MCLR
SLEEP
WDT ^WDT
Module _Time-out
Reset
VDD Rise
Detect
VDD
Power-on Reset
Brown-out
Reset
BODEN
S
OST/PWRT
OST
10-bit Ripple Counter
R
OSC1
(Note 1) _PWRT
On-chip
RC OSC
10-bit Ripple Counter
Chip Reset
Q
Enable PWRT
Enable OST
Note 1: This is a separate oscillator from the RC oscillator of the CLKIN pin.
DS30605C-page 88
 2000 Microchip Technology Inc.