PIC16F684 datasheet(103/192 Pages) MICROCHIP

103 / 192 page

DS41202F-page 101

PIC16F684

12.3.4

BROWN-OUT RESET (BOR)

The BOREN0 and BOREN1 bits in the Configuration

Word register select one of four BOR modes. Two

modes have been added to allow software or hardware

control of the BOR enable. When BOREN<1:0> = 01,

the SBOREN bit of the PCON register enables/disables

the BOR, allowing it to be controlled in software. By

selecting BOREN<1:0> = 10, the BOR is automatically

disabled in Sleep to conserve power and enabled on

wake-up. In this mode, the SBOREN bit is disabled.

See

for

the

Configuration

Word

definition.

A brown-out occurs when VDD falls below VBOR for

greater than parameter TBOR (see Section 15.0

“Electrical Specifications”). The brown-out condition

will reset the device. This will occur regardless of VDD

slew rate. A Brown-out Reset may not occur if VDD falls

below VBOR for less than parameter TBOR.

On any Reset (Power-on, Brown-out Reset, Watchdog

Timer, etc.), the chip will remain in Reset until VDD rises

above VBOR (see Figure 12-3). If enabled, the

Power-up Timer will be invoked by the Reset and keep

the chip in Reset an additional 64 ms.

If VDD drops below VBOR while the Power-up Timer is

running, the chip will go back into a Brown-out Reset

and the Power-up Timer will be re-initialized. Once VDD

rises above VBOR, the Power-up Timer will execute a

64 ms Reset.

12.3.5

BOR CALIBRATION

The PIC16F684 stores the BOR calibration values in

fuses located in the Calibration Word register (2008h).

The Calibration Word register is not erased when using

the

specified

bulk

erase

sequence

the

“PIC12F6XX/16F6XX Memory Programming Specifi-

cation”

(DS41204)

and

thus,

does

not

require

reprogramming.

FIGURE 12-3:

BROWN-OUT SITUATIONS

Note:

The Power-up Timer is enabled by the

PWRTE bit in the Configuration Word

Note:

Address 2008h is beyond the user pro-

gram memory space. It belongs to the

special

configuration

memory

space

(2000h-3FFFh), which can be accessed

only

during

programming.

See

“PIC12F6XX/16F6XX Memory Program-

ming Specification” (DS41204) for more

information.

64 ms(1)

VBOR

VDD

Internal

Reset

VBOR

VDD

Internal

Reset

64 ms(1)

< 64 ms

64 ms(1)

VBOR

VDD

Internal

Reset

Note 1:

64 ms delay only if PWRTE bit is programmed to ‘0’.

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