PIC16C54B-20/SO Microchip Technology, PIC16C54B-20/SO Datasheet - Page 34

• Manufacturer Part Number: PIC16C54B-20/SO
• Description: MICRO CTRL 512 20MHZ OTP 18SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16C54B-20/SO

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Peripherals: POR, WDT
• Number Of I /o: 12
• Program Memory Size: 768B (512 x 12)
• Program Memory Type: OTP
• Ram Size: 25 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 18-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Eeprom Size: -
• Data Converters: -
• Connectivity: -

PIC16C5X
7.2.3
Either a prepackaged oscillator or a simple oscillator
circuit with TTL gates can be used as an external
crystal oscillator circuit. Prepackaged oscillators
provide a wide operating range and better stability. A
well-designed crystal oscillator will provide good
performance with TTL gates. Two types of crystal
oscillator circuits can be used: one with parallel
resonance, or one with series resonance.
Figure 7-5 shows implementation of 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
provides the negative feedback for stability. The 10 k
potentiometers bias the 74AS04 in the linear region.
This circuit could be used for external oscillator
designs.
FIGURE 7-5:
This circuit is also designed to use the fundamental
frequency of the crystal. The inverter performs a
180-degree phase shift in a series resonant oscillator
circuit. The 330
feedback to bias the inverters in their linear region.
DS30453B-page 34
Note:
10k
EXTERNAL CRYSTAL OSCILLATOR
CIRCUIT
+5V
If you change from this device to
another device, please verify oscillator
characteristics in your application.
20 pF
10k
74AS04
XTAL
4.7k
EXTERNAL PARALLEL
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
(USING XT, HS OR LP
OSCILLATOR MODE)
resistors provide the negative
20 pF
10k
74AS04
To Other
Devices
100k
PIC16C5X
OSC2
OSC1
resistor
Preliminary
FIGURE 7-6:
7.2.4
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) and 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 will also affect the oscillation frequency,
especially for low Cext values. The user also needs to
take into account variation due to tolerance of external
R and C components used.
Figure 7-7 shows how the R/C combination is
connected to the PIC16C5X. 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 no or
small external capacitance, the oscillation frequency
can vary dramatically due to changes in external
capacitances, such as PCB trace capacitance or
package lead frame capacitance.
Note:
74AS04
330
RC OSCILLATOR
parameter
If you change from this device to
another device, please verify oscillator
characteristics in your application.
0.1 F
XTAL
EXTERNAL SERIES
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
(USING XT, HS OR LP
OSCILLATOR MODE)
74AS04
330
variation.
1998 Microchip Technology Inc.
74AS04
Furthermore,
To Other
Devices
100k
PIC16C5X
OSC2
OSC1
the