PIC16F628-04I/P Microchip Technology Inc., PIC16F628-04I/P Datasheet - Page 96

• Manufacturer Part Number: PIC16F628-04I/P
• Description: 18 PIN, 3.5 KB FLASH, 224 RAM, 16 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F628-04I/P

• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 128 Bytes
• Input Output: 16
• Interface: SCI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 18-pin PDIP
• Programmable Memory: 3.5K Bytes
• Ram Size: 224 Bytes
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC16F62X
FIGURE 14-2:
Figure 14-3 shows a series resonant oscillator circuit.
This circuit is also designed to use the fundamental
frequency of the crystal. The inverter performs a 180°
phase shift in a series resonant oscillator circuit. The
330 kΩ resistors provide the negative feedback to bias
the inverters in their linear region.
FIGURE 14-3:
14.2.4
For applications, where a clock is already available
elsewhere, users may directly drive the PIC16F62X
provided that this external clock source meets the
AC/DC timing requirements listed in Section 17.4.
Figure 14-4 shows how an external clock circuit should
be configured.
FIGURE 14-4:
DS40300C-page 94
74AS04
Clock From
ext. system
330 KΩ
10K
RA6
+5V
10K
EXTERNAL CLOCK IN
C1
0.1 PF
XTAL
74AS04
XTAL
4.7K
74AS04
C2
330 KΩ
EXTERNAL PARALLEL
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
EXTERNAL SERIES
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
EXTERNAL CLOCK INPUT
OPERATION (EC, HS, XT
OR LP OSC
CONFIGURATION)
10K
74AS04
OSC1/RA7
OSC2/RA6
74AS04
PIC16F62X
TO OTHER
DEVICES
TO OTHER
DEVICES
PIC16F62X
CLKIN
PIC16F62X
CLKIN
Preliminary
14.2.5
For timing insensitive applications, the ER (External
Resistor) Clock mode offers additional cost savings.
Only one external component, a resistor to V
needed to set the operating frequency of the internal
oscillator. The resistor draws a DC bias current which
controls the oscillation frequency. In addition to the
resistance value, the oscillator frequency will vary from
unit to unit, and as a function of supply voltage and
temperature. Since the controlling parameter is a DC
current and not a capacitance, the particular package
type and lead frame will not have a significant effect on
the resultant frequency.
Figure 14-5 shows how the controlling resistor is
connected to the PIC16F62X. For R
10k, the oscillator operation becomes sensitive to
temperature. For very high R
oscillator becomes sensitive to leakage and may stop
completely. Thus, we recommend keeping R
between 10k and 1M.
FIGURE 14-5:
Table 14-3 shows the relationship between the
resistance value and the operating frequency.
TABLE 14-3:
The ER Oscillator mode has two options that control
the unused OSC2 pin. The first allows it to be used as
a general purpose I/O port. The other configures the
pin as an output providing the F
clock divided by 4) for test or external synchronization
purposes.
Resistance
100K
220K
470K
10K
20K
47K
ER OSCILLATOR
1M
1K
0
RESISTANCE AND
FREQUENCY RELATIONSHIP
EXTERNAL RESISTOR
 2003 Microchip Technology Inc.
RA7/OSC1/CLKIN
RA6/OSC2/CLKOUT
EXT
values (e.g., 1M), the
OSC
Frequency
10.4 MHz
7.4 MHz
5.3 MHz
1.6 MHz
800 kHz
300 kHz
200 kHz
EXT
10 MHz
3 MHz
signal (internal
values below
SS
EXT
, is