PIC16F636-I/P Microchip Technology Inc., PIC16F636-I/P Datasheet - Page 31

• 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

3.0
3.1
The PIC12F635/PIC16F636/639 has a wide variety of
clock sources and selection features to allow it to be
used in a wide range of applications, while maximizing
performance and minimizing power consumption.
Figure 3-1
PIC12F635/PIC16F636/639 clock sources.
Clock sources can be configured from external oscillators,
quartz crystal resonators, ceramic resonators and
Resistor-Capacitor (RC) circuits. In addition, the system
clock source can be configured from one of two internal
oscillators, with a choice of speeds selectable via
software. Additional clock features include:
• Selectable system clock source between external
• Two-Speed Clock Start-up mode, which
• Fail-Safe Clock Monitor (FSCM) designed to
FIGURE 3-1:
© 2005 Microchip Technology Inc.
or internal via software.
minimizes latency between external oscillator
start-up and code execution.
detect a failure of the external clock source (LP,
XT, HS, EC or RC modes) and switch to the
internal oscillator.
OSC2
OSC1
Note 1:
CLOCK SOURCES
Overview
illustrates
2:
External Oscillator
Internal Oscillator
HFINTOSC = High-Frequency Calibrated Internal Oscillator.
LFINTOSC = Low-Frequency Internal Oscillator is not calibrated.
HFINTOSC
LFINTOSC
31 kHz
8 MHz
PIC12F635/PIC16F636/639 CLOCK SOURCE BLOCK DIAGRAM
a
(2)
(1)
block
Sleep
diagram
of
500 kHz
250 kHz
125 kHz
31 kHz
8 MHz
4 MHz
2 MHz
1 MHz
PIC12F635/PIC16F636/639
Preliminary
the
(OSCCON<6:4>)
IRCF<2:0>
111
110
101
100
011
010
001
000
The PIC12F635/PIC16F636/639 can be configured in
one of eight clock modes.
1.
2.
3.
4.
5.
6.
7.
8.
Clock source modes are configured by the FOSC<2:0>
bits
Section 12.0 “Special Features of the CPU”). The
internal clock can be generated by two oscillators. The
HFINTOSC is a high-frequency calibrated oscillator. The
LFINTOSC is a low-frequency uncalibrated oscillator.
LP, XT, HS, RC, RCIO, EC
EC – External clock with I/O on RA4.
LP – Low gain crystal or Ceramic Resonator
Oscillator mode.
XT – Medium gain crystal or Ceramic Resonator
Oscillator mode.
HS – High gain crystal or Ceramic Resonator
mode.
RC – External Resistor-Capacitor (RC) with
F
RCIO – External Resistor-Capacitor (RC) with I/O
on RA4.
INTOSC – Internal oscillator with F
on RA4 and I/O on RA5.
INTOSCIO – Internal oscillator with I/O on RA4
and RA5.
OSC
in
/4 output on RA4.
the
Power-up Timer (PWRT)
Watchdog Timer (WDT)
Fail-Safe Clock Monitor (FSCM)
Configuration
(Configuration Word)
(OSCCON<0>)
FOSC<2:0>
SCS
(CPU and Peripherals)
Word
DS41232B-page 29
System Clock
OSC
register
/4 output
(see