PIC18F2320-I/SP Microchip Technology Inc., PIC18F2320-I/SP Datasheet - Page 29

• Manufacturer Part Number: PIC18F2320-I/SP
• Description: Microcontroller; 8 KB Flash; 512 RAM; 256 EEPROM; 25 I/O; 28-Pin-SPDIP
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F2320-I/SP

• A/d Inputs: 10-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 10 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 25
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 8K Bytes
• Ram Size: 512 Bytes
• Speed: 20 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

2.7.2
The PIC18F2X20/4X20 devices contain circuitry to pre-
vent clocking “glitches” when switching between clock
sources. A short pause in the system clock occurs dur-
ing the clock switch. The length of this pause is
between 8 and 9 clock periods of the new clock source.
This ensures that the new clock source is stable and
that its pulse width will not be less than the shortest
pulse width of the two clock sources.
Clock transitions are discussed in greater detail in
Section 3.1.2 “Entering Power Managed Modes”.
2.8
When the device executes a SLEEP instruction, the
system is switched to one of the power managed
modes, depending on the state of the IDLEN and
SCS1:SCS0 bits of the OSCCON register. See
Section 3.0 “Power Managed Modes” for details.
When PRI_IDLE mode is selected, the designated pri-
mary oscillator continues to run without interruption.
For all other power managed modes, the oscillator
using the OSC1 pin is disabled. The OSC1 pin (and
OSC2 pin, if used by the oscillator) will stop oscillating.
In
SEC_IDLE), the Timer1 oscillator is operating and pro-
viding the system clock. The Timer1 oscillator may also
run in all power managed modes if required to clock
Timer1 or Timer3.
In internal oscillator modes (RC_RUN and RC_IDLE),
the internal oscillator block provides the system clock
source. The INTRC output can be used directly to
provide the system clock and may be enabled to
support various special features, regardless of the
power managed mode (see Section 23.2 “Watchdog
Timer (WDT)” through Section 23.4 “Fail-Safe Clock
Monitor”). The INTOSC output at 8 MHz may be used
directly to clock the system or may be divided down
first. The INTOSC output is disabled if the system clock
is provided directly from the INTRC output.
TABLE 2-3:
 2003 Microchip Technology Inc.
RC, INTIO1
RCIO, INTIO2
ECIO
EC
LP, XT, and HS
Note:
secondary
Effects of Power Managed Modes
on the Various Clock Sources
OSCILLATOR TRANSITIONS
See Table 4-1 in Section 4.0 “Reset” for time-outs due to Sleep and MCLR Reset.
OSC Mode
clock
OSC1 AND OSC2 PIN STATES IN SLEEP MODE
modes
(SEC_RUN
Floating, external resistor
should pull high
Floating, external resistor
should pull high
Floating, pulled by external clock
Floating, pulled by external clock
Feedback inverter disabled at
quiescent voltage level
PIC18F2220/2320/4220/4320
and
OSC1 Pin
If the Sleep mode is selected, all clock sources are
stopped. Since all the transistor switching currents
have been stopped, Sleep mode achieves the lowest
current consumption of the device (only leakage
currents).
Enabling any on-chip feature that will operate during
Sleep will increase the current consumed during Sleep.
The INTRC is required to support WDT operation. The
Timer1 oscillator may be operating to support a real-
time clock. Other features may be operating that do not
require a system clock source (i.e., SSP slave, PSP,
INTn pins, A/D conversions and others).
2.9
Power-up delays are controlled by two timers so that no
external Reset circuitry is required for most applica-
tions. The delays ensure that the device is kept in
Reset until the device power supply is stable under nor-
mal circumstances and the primary clock is operating
and stable. For additional information on power-up
delays, see Section 4.1 “Power-on Reset (POR)”
through Section 4.5 “Brown-out Reset (BOR)”.
The first timer is the Power-up Timer (PWRT) which
provides a fixed delay on power-up (parameter 33,
Table 26-10), if enabled, in Configuration Register 2L.
The second timer is the Oscillator Start-up Timer
(OST), intended to keep the chip in Reset until the crys-
tal oscillator is stable (LP, XT and HS modes). The OST
does this by counting 1024 oscillator cycles before
allowing the oscillator to clock the device.
When the HSPLL Oscillator mode is selected, the
device is kept in Reset for an additional 2 ms, following
the HS mode OST delay, so the PLL can lock to the
incoming clock frequency.
There is a delay of 5 to 10 s, following POR, while the
controller becomes ready to execute instructions. This
delay runs concurrently with any other delays. This
may be the only delay that occurs when any of the EC,
RC or INTIO modes are used as the primary clock
source.
Power-up Delays
Configured as PORTA, bit 6
At logic low (clock/4 output)
Configured as PORTA, bit 6
At logic low (clock/4 output)
Feedback inverter disabled at
quiescent voltage level
OSC2 Pin
DS39599C-page 27