PIC16LC72T-10IP 查看數據表（PDF） - Microchip Technology

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PIC16LC72T-10IP

8-Bit CMOS Microcontrollers with A/D Converter

Microchip Technology 

PIC16C7X

14.3 Reset

Applicable Devices

72 73 73A 74 74A 76 77

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) (PIC16C72/73A/74A/76/

77)

Some registers are not affected in any reset condition;

their status is unknown on POR and unchanged in any

other reset. Most other registers are reset to a “reset

state” on Power-on Reset (POR), on the MCLR and

WDT Reset, on MCLR reset during SLEEP, and Brown-

out Reset (BOR). They are not affected by a WDT

Wake-up, which is viewed as the resumption of normal

operation. The TO and PD bits are set or cleared differ-

ently in different reset situations as indicated in

Table 14-5 and Table 14-6. These bits are used in soft-

ware to determine the nature of the reset. See

Table 14-8 for a full description of reset states of all reg-

isters.

A simplified block diagram of the on-chip reset circuit is

shown in Figure 14-8.

The PIC16C72/73A/74A/76/77 have a MCLR noise fil-

ter in the MCLR reset path. The filter will detect and

ignore small pulses.

It should be noted that a WDT Reset does not drive

MCLR pin low.

FIGURE 14-8: SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT

External

Reset

MCLR

VDD

SLEEP

WDT WDT

Module Time-out

Reset

VDD rise

detect

(2) Power-on Reset

Brown-out

Reset BODEN

OSC1

OST/PWRT

OST

10-bit Ripple counter

(1) PWRT

On-chip

RC OSC

10-bit Ripple counter

S

Chip_Reset

R

Q

Enable PWRT

(3)

Enable OST

Note 1: This is a separate oscillator from the RC oscillator of the CLKIN pin.

2: Brown-out Reset is implemented on the PIC16C72/73A/74A/76/77.

3: See Table 14-3 and Table 14-4 for time-out situations.

© 1997 Microchip Technology Inc.

DS30390E-page 133

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