PIC16C745/JW Microchip Technology, PIC16C745/JW Datasheet - Page 103

• Manufacturer Part Number: PIC16C745/JW
• Description: IC MCU EPROM8KX14 USB A/D 28CDIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16C745/JW

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 24MHz
• Connectivity: SCI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 14KB (8K x 14)
• Program Memory Type: EPROM, UV
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4.35 V ~ 5.25 V
• Data Converters: A/D 5x8b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 28-CDIP (0.300", 7.62mm) Window
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

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 pin
directly (or through a resistor) to V
nate external RC components usually needed to create
a POR. A maximum rise time for V
Electrical Specifications for details.
When the device starts normal operation (exits the
RESET condition), device operating parameters (volt-
age, 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 from the POR. The PWRT oper-
ates on an internal RC oscillator. The device is kept in
RESET as long as the PWRT is active. The PWRT’s
time delay allows V
configuration bit is provided to enable/disable the
PWRT.
The power-up time delay will vary from chip to chip due
to V
parameters for details (T
13.4.3
The Oscillator Start-up Timer provides a delay of 1024
oscillator cycles (from OSC1 input) after the PWRT
delay. This ensures that the crystal oscillator or resona-
tor has started and stabilized.
The OST time-out is invoked only for HS mode and
only on Power-on Reset or wake-up from SLEEP.
DD
2000 Microchip Technology Inc.
DD
rise is detected (in the range of 1.5V - 2.1V). To
, temperature and process variation. See DC
RESETS
POWER-ON RESET (POR)
POWER-UP TIMER (PWRT)
OSCILLATOR START-UP TIMER (OST)
DD
to rise to an acceptable level. A
PWRT
, parameter #33).
DD
DD
is specified. See
. This will elimi-
Preliminary
13.4.4
If V
than T
will reset the device. If V
than T
Once the brown-out occurs, the device will remain in
Brown-out Reset until V
Power-up Timer then keeps the device in RESET for
T
during T
restart when V
up Timer Reset. Since the device is intended to oper-
ate at 5V nominal only, the Brown-out Detect is always
enabled and the device will RESET when Vdd falls
below the brown-out threshold. This device is unique
in that the 4 WDT timer will not activate after a brown-
out if PWRTE = 1 (inactive).
13.4.5
On power-up, the time-out sequence is as follows: The
PWRT delay starts (if enabled), when a Power-on
Reset occurs. Then OST starts counting 1024 oscillator
cycles when PWRT ends (HS). When the OST ends,
the device comes out of RESET.
If MCLR is kept low long enough, the time-outs will
expire. Bringing MCLR high will begin execution imme-
diately. This is useful for testing purposes or to synchro-
nize more than one PIC16CXX device operating in
parallel.
Table 13-5 shows the RESET conditions for the STA-
TUS, PCON and PC registers, while Table 13-7 shows
the RESET conditions for all the registers.
13.4.6
The Brown-out Reset Status bit, BOR, is unknown on a
POR. It must be set by the user and checked on sub-
sequent RESETS to see if bit BOR was cleared, indi-
cating a BOR occurred. The BOR bit is not predictable
if the Brown-out Reset circuitry is disabled.
The Power-on Reset Status bit, POR, is cleared on a
POR and unaffected otherwise. The user must set this
bit following a POR and check it on subsequent
RESETS to see if it has been cleared.
PWRT
DD
BOR
BOR
falls below V
(parameter #33). If V
TIME-OUT SEQUENCE
POWER CONTROL/STATUS REGISTER
BROWN-OUT RESET (BOR)
(PCON)
PWRT
, a RESET may not occur.
(parameter #35), the brown-out situation
PIC16C745/765
, the Brown-out Reset process will
DD
rises above V
BOR
(parameter D005) for longer
DD
DD
DD
falls below V
rises above V
should fall below V
BOR
DS41124C-page 103
, with the Power-
BOR
BOR
for less
. The
BOR