PIC16C63A Microchip Technology, PIC16C63A Datasheet - Page 85

• Manufacturer Part Number: PIC16C63A
• Description: 28/40-Pin 8-Bit CMOS Microcontrollers
• Manufacturer: Microchip Technology

11.4
A Power-on Reset pulse is generated on-chip when
V
take advantage of the POR, just tie the MCLR pin
directly (or through a resistor) to V
external RC components usually needed to create a
Power-on Reset. A maximum rise time for V
ified (parameter D004). For a slow rise time, see
Figure 11-6.
When the device starts normal operation (exits the
reset condition), device operating parameters (voltage,
frequency, temperature,...) must be met to ensure oper-
ation. 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 start-up con-
ditions.
FIGURE 11-6: EXTERNAL POWER-ON
Note 1: External Power-on Reset circuit is required
DD
1998 Microchip Technology Inc.
rise is detected (in the range of 1.5V - 2.1V). To
2: R < 40 k is recommended to make sure
3: R1 = 100 to 1 k will limit any current
Power-On Reset (POR)
only if V
diode D helps discharge the capacitor
quickly when V
that voltage drop across R does not violate
the device’s electrical specification.
flowing into MCLR from external capacitor
C in the event of MCLR/V
down due to Electrostatic Discharge
(ESD) or Electrical Overstress (EOS).
D
V
DD
RESET CIRCUIT (FOR SLOW
V
DD
R
DD
C
power-up slope is too slow. The
POWER-UP)
DD
R1
powers down.
DD
PIC16CXXX
MCLR
PP
. This will eliminate
pin break-
DD
is spec-
PIC16C63A/65B/73B/74B
11.5
The Power-up Timer provides a fixed nominal time-out
(parameter #33) on power-up only, from the POR. The
Power-up Timer operates on an internal RC oscillator.
The chip is kept in reset as long as the PWRT is active.
The PWRT’s time delay allows V
able level. A configuration bit is provided to enable/dis-
able the PWRT.
The power-up time delay will vary from chip to chip due
to V
parameters for details.
11.6
The Oscillator Start-up Timer (OST) provides 1024
oscillator cycle (from OSC1 input) delay after the
PWRT delay is over (parameter #32). This ensures that
the crystal oscillator or resonator has started and sta-
bilized.
The OST time-out is invoked only for XT, LP and HS
modes and only on Power-on Reset or wake-up from
SLEEP.
11.7
A configuration bit, BODEN, can disable (if clear/pro-
grammed) or enable (if set) the Brown-out Reset cir-
cuitry. If V
than parameter #35, the brown-out situation will reset
the chip. A reset may not occur if V
parameter D005 for less than parameter #35. The chip
will remain in Brown-out Reset until V
BV
keep the chip in RESET an additional time delay
(parameter #33). If V
Power-up Timer is running, the chip will go back into a
Brown-out Reset and the Power-up Timer will be initial-
ized. Once V
will execute the additional time delay. The Power-up
Timer should always be enabled when Brown-out
Reset is enabled.
DD
DD
. The Power-up Timer will then be invoked and will
, temperature and process variation. See DC
Power-up Timer (PWRT)
Oscillator Start-up Timer (OST)
Brown-Out Reset (BOR)
DD
DD
falls below parameter D005 for greater
rises above BV
DD
drops below BV
DD
DD
, the Power-up Timer
to rise to an accept-
DS30605A-page 85
DD
DD
DD
rises above
falls below
while the