PIC16F636-I/P Microchip Technology Inc., PIC16F636-I/P Datasheet - Page 33

• Manufacturer Part Number: PIC16F636-I/P
• Description: 14 PIN, 3.5 KB FLASH, 128 RAM, 12 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F636-I/P

• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 12
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 14-pin PDIP
• Programmable Memory: 3.5K Bytes
• Ram Size: 128 Bytes
• Speed: 20 MHz
• Timers: 1-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

3.3.2
The External Clock (EC) mode allows an externally
generated logic level as the system clock source.
When operating in this mode, an external clock source
is connected to the OSC1 pin and the RA5 pin is
available for general purpose I/O. Figure 3-2 shows the
pin connections for EC mode.
The Oscillator Start-up Timer (OST) is disabled when
EC mode is selected. Therefore, there is no delay in
operation after a Power-on Reset (POR) or wake-up
from Sleep. Because the PIC12F635/PIC16F636/639
design is fully static, stopping the external clock input
will have the effect of halting the device while leaving all
data intact. Upon restarting the external clock, the
device will resume operation as if no time had elapsed.
FIGURE 3-2:
3.3.3
The LP, XT and HS modes support the use of quartz
crystal resonators or ceramic resonators connected to
the OSC1 and OSC2 pins (Figure 3-1). The mode
selects a low, medium or high gain setting of the
internal inverter-amplifier to support various resonator
types and speed.
LP Oscillator mode selects the lowest gain setting of
the internal inverter-amplifier. LP mode current
consumption is the least of the three modes. This mode
is best suited to drive resonators with a low drive level
specification, for example, tuning fork type crystals.
XT Oscillator mode selects the intermediate gain
setting of the internal inverter-amplifier. XT mode
current consumption is the medium of the three modes.
This mode is better suited to drive resonators with a
medium drive level specification, for example, low-
frequency AT-cut quartz crystal resonators.
HS Oscillator mode selects the highest gain setting of
the internal inverter-amplifier. HS mode current
consumption is the highest of the three modes. This
mode is better suited for resonators that require a high
drive setting, for example, high-frequency AT-cut
quartz crystal resonators or ceramic resonators.
Figure 3-3 and Figure 3-4 show typical circuits for
quartz crystal and ceramic resonators, respectively.
© 2005 Microchip Technology Inc.
Clock from
Ext. System
EC MODE
LP, XT, HS MODES
RA4
EXTERNAL CLOCK (EC)
MODE OPERATION
OSC1/CLKIN
I/O (OSC2)
PIC12F635/PIC16F636/639
PIC12F635/PIC16F636/639
Preliminary
FIGURE 3-3:
FIGURE 3-4:
Note 1: A series resistor (R
Note 1: Quartz
Note 1: A series resistor (R
C1
C2
C1
C2 Ceramic
2: The value of R
3: An additional parallel feedback resistor (R
2: Always verify oscillator performance over
2: The value of R
Resonator
ceramic resonators with low drive level.
mode selected (typically between 2 M
10 M
may be required for proper ceramic resonator
operation (typical value 1 M ).
according
manufacturer. The user should consult the
manufacturer data sheets for specifications
and recommended application.
the V
expected for the application.
quartz crystals with low drive level.
mode selected (typically between 2 M
10 M
Quartz
Crystal
R
S (1)
OSC1
OSC2
R
.
DD
P
R
OSC1
(3)
OSC2
.
S
(1)
and temperature range that is
QUARTZ CRYSTAL
OPERATION (LP, XT OR
HS MODE)
crystal
CERAMIC RESONATOR
OPERATION
(XT OR HS MODE)
to
PIC12F635/PIC16F636/639
F
PIC12F635/PIC16F636/639
F
R
varies with the Oscillator
F
varies with the Oscillator
(2)
R
S
type,
F (2)
S
) may be required for
) may be required for
characteristics
DS41232B-page 31
package
Sleep
Sleep
To Internal
To Internal
Logic
Logic
vary
to
P
and
to
)