PIC16C84-04/P Microchip Technology, PIC16C84-04/P Datasheet - Page 37

• Manufacturer Part Number: PIC16C84-04/P
• Description: MICRO CTRL 1KX14 EPR EEPR 18DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16C84-04/P

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 4MHz
• Peripherals: POR, WDT
• Number Of I /o: 13
• Program Memory Size: 1.75KB (1K x 14)
• Program Memory Type: EEPROM
• Eeprom Size: 64 x 8
• Ram Size: 36 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 6 V
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 18-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Data Converters: -
• Connectivity: -

8.2.3
Either a prepackaged oscillator can be used or a simple
oscillator circuit with TTL gates can be built.
Prepackaged oscillators provide a wide operating
range and better stability. A well-designed crystal
FIGURE 8-4:
Figure 8-5 shows a series resonant oscillator circuit.
This circuit is also designed to use the fundamental
frequency of the crystal. The inverter performs a 180-
degree phase shift. The 330 k
negative feedback to bias the inverters in their linear
region.
FIGURE 8-5:
oscillator will provide good performance with TTL
gates. Two types of crystal oscillator circuits are
available; one with series resonance, and one with
parallel resonance.
Figure 8-4 shows a parallel resonant oscillator circuit.
The circuit is designed to use the fundamental
frequency of the crystal. The 74AS04 inverter performs
the 180-degree phase shift that a parallel oscillator
requires. The 4.7 k
feedback for stability. The 10 k
the 74AS04 in the linear region. This could be used for
external oscillator designs.
1997 Microchip Technology Inc.
74AS04
330 k
10k
EXTERNAL CRYSTAL OSCILLATOR
CIRCUIT
+5V
20 pF
0.1 F
XTAL
10k
74AS04
XTAL
4.7k
EXTERNAL PARALLEL
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
EXTERNAL SERIES
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
74AS04
330 k
20 pF
resistor provides negative
10k
74AS04
74AS04
potentiometer biases
resistors provide the
To Other
Devices
To Other
Devices
CLKIN
PIC16CXX
PIC16CXX
CLKIN
8.2.4
For timing insensitive applications the RC device option
offers additional cost savings. The RC oscillator
frequency is a function of the supply voltage, the
resistor (Rext) values, capacitor (Cext) values, and the
operating temperature. In addition to this, the oscillator
frequency will vary from unit to unit due to normal
process
difference in lead frame capacitance between package
types also affects the oscillation frequency, especially
for low Cext values. The user needs to take into
account variation due to tolerance of the external
R and C components. Figure 8-6 shows how an R/C
combination is connected to the PIC16C84. For Rext
values below 2.2 k , the oscillator operation may
become unstable, or stop completely. For very high
Rext values (e.g., 1 M ), the oscillator becomes
sensitive to noise, humidity and leakage. Thus, we
recommend keeping Rext between 3 k and 100 k .
Although the oscillator will operate with no external
capacitor (Cext = 0 pF), we recommend using values
above 20 pF for noise and stability reasons. With little
or no external capacitance, the oscillation frequency
can vary dramatically due to changes in external
capacitances, such as PCB trace capacitance or
package lead frame capacitance.
See the electrical specification section for RC
frequency variation from part to part due to normal
process variation. The variation is larger for larger R
(since leakage current variation will affect RC
frequency more for large R) and for smaller C (since
variation of input capacitance has a greater affect on
RC frequency).
See the electrical specification section for variation of
oscillator frequency due to V
values as well as frequency variation due to
operating temperature.
The oscillator frequency, divided by 4, is available on
the OSC2/CLKOUT pin, and can be used for test
purposes or to synchronize other logic (see Figure 3-2
for waveform).
FIGURE 8-6:
Cext
V
Recommended values: 3 k
Rext
Note:
SS
V
DD
RC OSCILLATOR
parameter
When the device oscillator is in RC mode,
do not drive the OSC1 pin with an external
clock or you may damage the device.
Fosc/4
RC OSCILLATOR MODE
variation.
OSC1
OSC2/CLKOUT
Cext > 20pF
PIC16C84
DD
Rext
for given Rext/Cext
Furthermore,
DS30445C-page 37
100 k
PIC16CXX
Internal
clock
the