PIC16F648A-I/ML Microchip Technology, PIC16F648A-I/ML Datasheet - Page 100

• Manufacturer Part Number: PIC16F648A-I/ML
• Description: IC MCU FLASH 4KX14 EEPROM 28QFN
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F648A-I/ML

• Core Size: 8-Bit
• Program Memory Size: 7KB (4K x 14)
• Oscillator Type: Internal
• Core Processor: PIC
• Speed: 20MHz
• Connectivity: UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Controller Family/series: PIC16F
• No. Of I/o's: 16
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 256Byte
• Cpu Speed: 20MHz
• No.: RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AC164324 - MODULE SKT FOR MPLAB 8DFN/16QFNXLT28QFN3 - SOCKET TRAN ICE 18DIP/28QFNI3DBF648 - BOARD DAUGHTER ICEPIC3AC164033 - ADAPTER 28QFN TO 18DIPDV007003 - PROGRAMMER UNIVERSAL PROMATE II
• Data Converters: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PIC16F627A/628A/648A
14.2.3
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
oscillator will provide good performance with TTL
gates. Two types of crystal oscillator circuits can be
used; one with series resonance, or one with parallel
resonance.
Figure 14-2 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 phase shift that a
parallel oscillator requires. The 4.7 k
provides the negative feedback for stability. The
10 k
region. This could be used for external oscillator
designs.
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 k resistors provide the negative feedback to bias
the inverters in their linear region.
DS40044D-page 98
10K
+5V
potentiometers bias the 74AS04 in the linear
10K
C1
74AS04
XTAL
4.7K
EXTERNAL CRYSTAL OSCILLATOR
CIRCUIT
C2
10K
EXTERNAL PARALLEL
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
74AS04
To other
Devices
PIC16F627A/628A/648A
CLKIN
resistor
FIGURE 14-3:
14.2.4
The internal precision oscillator provides a fixed 4 MHz
(nominal) system clock at V
Section 17.0 “Electrical Specifications”, for informa-
tion on variation over voltage and temperature.
14.2.5
For applications where a clock is already available
elsewhere, users may directly drive the PIC16F627A/
628A/648A provided that this external clock source meets
the AC/DC timing requirements listed in Section 17.6
“Timing Diagrams and Specifications”. Figure 14-4
below shows how an external clock circuit should be
configured.
FIGURE 14-4:
74AS04
Clock from
ext. system
330 K
RA6
PRECISION INTERNAL 4 MH
OSCILLATOR
EXTERNAL CLOCK IN
0.1 pF
XTAL
74AS04
330 K
EXTERNAL SERIES
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
EXTERNAL CLOCK INPUT
OPERATION (EC, HS, XT
OR LP OSC
CONFIGURATION)
© 2005 Microchip Technology Inc.
RA6/OSC2/CLKOUT
RA7/OSC1/CLKIN
PIC16F627A/628A/648A
DD
74AS04
= 5V and 25 C. See
To other
Devices
PIC16F627A/
628A/648A
Z
CLKIN