PIC18LF8490-I/PT Microchip Technology, PIC18LF8490-I/PT Datasheet - Page 57

• Manufacturer Part Number: PIC18LF8490-I/PT
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,TQFP,80PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18LF8490-I/PT

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, LCD, POR, PWM, WDT
• Number Of I /o: 66
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 80-TFQFP
• Processor Series: PIC18LF
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 768 B
• Interface Type: SPI, I2C, EUSART, AUSART
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 66
• Number Of Timers: 1 x 8
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, ICE4000, DV164136, DM163028
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 12 bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

4.5
PIC18F6390/6490/8390/8490
three separate on-chip timers that help regulate the
Power-on Reset process. Their main function is to
ensure that the device clock is stable before code is
executed. These timers are:
• Power-up Timer (PWRT)
• Oscillator Start-up Timer (OST)
• PLL Lock Time-out
4.5.1
The
PIC18F6390/6490/8390/8490 devices is an 11-bit
counter which uses the INTRC source as the clock
input. This yields an approximate time interval of
2048 x 32 μs = 65.6 ms. While the PWRT is counting,
the device is held in Reset.
The power-up time delay depends on the INTRC clock
and will vary from chip-to-chip due to temperature and
process variation. See DC parameter 33 for details.
The PWRT is enabled by clearing the PWRTEN
Configuration bit.
4.5.2
The Oscillator Start-up Timer (OST) provides a
1024 oscillator cycle (from OSC1 input) delay after the
PWRT delay is over (parameter 33). This ensures that
the crystal oscillator or resonator has started and is
stabilized.
The OST time-out is invoked only for XT, LP, HS and
HSPLL modes and only on Power-on Reset, or on exit
from most power-managed modes.
TABLE 4-2:
© 2007 Microchip Technology Inc.
HSPLL
HS, XT, LP
EC, ECIO
RC, RCIO
INTIO1, INTIO2
Note 1: 66 ms (65.5 ms) is the nominal Power-up Timer (PWRT) delay.
Configuration
2: 2 ms is the nominal time required for the PLL to lock.
Oscillator
Device Reset Timers
Power-up
POWER-UP TIMER (PWRT)
OSCILLATOR START-UP
TIMER (OST)
TIME-OUT IN VARIOUS SITUATIONS
Timer
66 ms
66 ms
(1)
devices
PWRTEN = 0
+ 1024 T
(1)
66 ms
66 ms
66 ms
(PWRT)
+ 1024 T
incorporate
Power-up
OSC
(1)
(1)
(1)
PIC18F6390/6490/8390/8490
+ 2 ms
OSC
of
(2)
(2)
and Brown-out
4.5.3
With the PLL enabled in its PLL mode, the time-out
sequence following a Power-on Reset is slightly
different from other oscillator modes. A separate timer
is used to provide a fixed time-out that is sufficient for
the PLL to lock to the main oscillator frequency. This
PLL lock time-out (T
the oscillator start-up time-out.
4.5.4
On power-up, the time-out sequence is as follows:
1.
2.
The total time-out will vary based on oscillator
configuration and the status of the PWRT. Figure 4-3,
Figure 4-4, Figure 4-5, Figure 4-6 and Figure 4-7 all
depict time-out sequences on power-up, with the
Power-up Timer enabled and the device operating in
HS Oscillator mode. Figures 4-3 through 4-6 also apply
to devices operating in XT or LP modes. For devices in
RC mode and with the PWRT disabled, on the other
hand, there will be no time-out at all.
Since the time-outs occur from the POR pulse, if MCLR
is kept low long enough, all time-outs will expire.
Bringing MCLR high will begin execution immediately
(Figure 4-5). This is useful for testing purposes, or to
synchronize more than one PIC18FXXXX device
operating in parallel.
1024 T
PWRTEN = 1
After the POR pulse has cleared, PWRT
time-out is invoked (if enabled).
Then, the OST is activated.
1024 T
OSC
—
—
—
PLL LOCK TIME-OUT
TIME-OUT SEQUENCE
+ 2 ms
OSC
(2)
PLL
) is typically 2 ms and follows
Power-Managed Mode
1024 T
1024 T
Exit from
DS39629C-page 55
OSC
—
—
—
+ 2 ms
OSC
(2)