PIC16C432-I View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16C432-I

OTP 8-Bit CMOS MCU with LIN Transceiver

Microchip Technology 

PIC16C432

9.4 Power-on Reset (POR), Power-up

Timer (PWRT), Oscillator Start-up

Timer (OST) and Brown-out Reset

(BOD)

9.4.1 POWER-ON RESET (POR)

The on-chip POR circuit holds the chip in RESET until

VDD has reached a high enough level for proper oper-

ation. To take advantage of the POR, just tie the MCLR

pin through a resistor to VDD. This will eliminate exter-

nal RC components usually needed to create Power-on

Reset. A maximum rise time for VDD is required. See

electrical specifications for details.

The POR circuit does not produce an internal RESET

when VDD declines.

When the device starts normal operation (exits the

RESET condition), device operating parameters (volt-

age, frequency, temperature, etc.) must be met to

ensure operation. If these conditions are not met, the

device must be held in RESET until the operating condi-

tions are met.

For additional information, refer to Application Note

AN607, “Power-up Trouble Shooting”.

9.4.2 POWER-UP TIMER (PWRT)

The Power-up Timer provides a fixed 72 ms (nominal)

timeout on power-up only, from POR or Brown-out

Reset. The Power-up Timer operates on an internal RC

oscillator. The chip is kept in RESET as long as PWRT

is active. The PWRT delay allows the VDD to rise to an

acceptable level. A configuration bit, PWRTE, can

disable (if set), or enable (if cleared or programmed)

the Power-up Timer. The Power-up Timer should

always be enabled when Brown-out Reset is enabled.

FIGURE 9-7:

BROWN-OUT SITUATIONS

The Power-Up time delay will vary from chip-to-chip

and due to VDD, temperature and process variation.

See DC parameters for details.

9.4.3

OSCILLATOR START-UP TIMER

(OST)

The Oscillator Start-up Timer (OST) provides a 1024

oscillator cycle (from OSC1 input) delay after the

PWRT delay is over. This ensures that the crystal

oscillator or resonator has started and stabilized.

The OST timeout is invoked only for XT, LP and HS

modes and only on Power-on Reset or wake-up from

SLEEP.

9.4.4 BROWN-OUT RESET (BOD)

The PIC16C432 has an on-chip Brown-out Reset cir-

cuitry. A configuration bit, BOREN, can disable (if clear/

programmed), or enable (if set) the Brown-out Reset

circuitry. If VDD falls below 4.0V (refer to BVDD param-

eter D005) for greater than parameter (TBOR) in

Table 12-6, the brown-out situation will reset the chip.

A RESET won’t occur if VDD falls below 4.0V for less

than parameter (TBOR).

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

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

above BVDD. The Power-up Timer will then be invoked

and will keep the chip in RESET an additional 72 ms.

If VDD drops below BVDD 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 BVDD, the Power-up Timer will execute a 72 ms

RESET. The Power-up Timer should always be enabled

when Brown-out Reset is enabled. Figure 9-7 shows

typical Brown-out situations.

VDD

Internal

Reset

VDD

Internal

Reset

72 ms

<72 ms

72 ms

BVDD

BVDD

VDD

Internal

Reset

72 ms

BVDD

DS41140C-page 48

Preliminary

 2000-2013 Microchip Technology Inc.

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