PIC16C65A Microchip Technology, PIC16C65A Datasheet - Page 129

• Manufacturer Part Number: PIC16C65A
• Description: 8-Bit CMOS Microcontrollers
• Manufacturer: Microchip Technology

13.4
13.4.1
A Power-on Reset pulse is generated on-chip when
V
take advantage of the POR, just tie the MCLR/V
directly (or through a resistor) to V
nate external RC components usually needed to create
a Power-on Reset. A maximum rise time for V
required. See Electrical Specifications for details.
When the device starts normal operation (exits the
reset condition), device operating parameters (voltage,
frequency, temperature, ...) must be met to ensure
operation. If these conditions are not met, the device
must be held in reset until the operating conditions are
met. Brown-out Reset may be used to meet the startup
conditions.
For additional information, refer to Application Note
AN607, “ Power-up Trouble Shooting .”
13.4.2
The Power-up Timer provides a fixed 72 ms nominal
time-out on power-up only, from POR. The Power-up
Timer operates on an internal RC oscillator. The chip is
kept in reset as long as PWRT is active. The PWRT’s
time delay allows V
configuration bit is provided to enable/disable the
PWRT.
FIGURE 13-10: BROWN-OUT SITUATIONS
Applicable Devices
61 62 62A R62 63 R63 64 64A R64 65 65A R65 66 67
DD
1997 Microchip Technology Inc.
rise is detected (in the range of 1.5V - 2.1V). To
Power-on Reset (POR), Power-up
Timer (PWRT), Oscillator Start-up
Timer (OST) and Brown-out Reset
(BOR)
POWER-ON RESET (POR)
POWER-UP TIMER (PWRT)
Internal
Reset
Internal
Reset
Internal
Reset
V
V
V
DD
DD
DD
DD
to rise to an acceptable level. A
DD
. This will elimi-
PP
DD
pin
is
<72 ms
72 ms
The power-up time delay will vary from chip to chip due
to V
parameters for details.
13.4.3
The Oscillator Start-up Timer (OST) provides 1024
oscillator cycle (from OSC1 input) delay after the
PWRT delay is over. This ensures the crystal oscillator
or resonator has started and stabilized.
The OST time-out is invoked only for XT, LP and HS
modes and only on Power-on Reset or wake-up from
SLEEP.
13.4.4
A configuration bit, BODEN, can disable (if clear/pro-
grammed) or enable (if set) the Brown-out Reset cir-
cuitry. If V
Electrical Specification section) for greater than param-
eter #34 (see Electrical Specification section), the
brown-out situation will reset the chip. A reset may not
occur if V
#34. The chip will remain in Brown-out Reset until V
rises above BV
invoked and will keep the chip in RESET an additional
72 ms. If V
Timer is running, the chip will go back into a Brown-out
Reset and the Power-up Timer will be initialized. Once
V
cute a 72 ms time delay. The Power-up Timer should
always be enabled when Brown-out Reset is enabled.
Figure 13-10 shows typical brown-out situations.
Applicable Devices
61 62 62A R62 63 R63 64 64A R64 65 65A R65 66 67
DD
72 ms
72 ms
DD
rises above BV
, temperature, and process variation. See DC
OSCILLATOR START-UP TIMER (OST)
BROWN-OUT RESET (BOR)
DD
DD
DD
falls below 4.0V for less than parameter
drops below BV
falls below 4.0V (parameter D005 in
DD
. The Power-up Timer will now be
DD
, the Power-up Timer will exe-
BV
BV
BV
BV
BV
BV
PIC16C6X
DD
DD
DD
DD
DD
DD
DD
Max.
Min.
Max.
Min.
Max.
Min.
while the Power-up
DS30234D-page 129
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