PIC16F88-I/SO Microchip Technology Inc., PIC16F88-I/SO Datasheet - Page 39

• Manufacturer Part Number: PIC16F88-I/SO
• Description: 18 PIN, 7 KB FLASH, 368 RAM, 16 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F88-I/SO

• A/d Inputs: 7-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 16
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 18-pin SOIC
• Programmable Memory: 7K Bytes
• Ram Size: 368 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

4.4
For timing insensitive applications, the “RC” and
“RCIO” device options offer additional cost savings.
The RC oscillator frequency is a function of the supply
voltage, the resistor (R
ues and the operating temperature. In addition to this,
the oscillator frequency will vary from unit to unit due to
normal manufacturing variation. Furthermore, the dif-
ference in lead frame capacitance between package
types will also affect the oscillation frequency,
especially for low C
take into account variation due to tolerance of external
R and C components used. Figure 4-4 shows how the
R/C combination is connected.
In the RC Oscillator mode, the oscillator frequency
divided by 4 is available on the OSC2 pin. This signal may
be used for test purposes or to synchronize other logic.
FIGURE 4-4:
The RCIO Oscillator mode (Figure 4-5) functions like
the RC mode, except that the OSC2 pin becomes an
additional general purpose I/O pin. The I/O pin
becomes bit 6 of PORTA (RA6).
FIGURE 4-5:
 2005 Microchip Technology Inc.
Recommended values: 3 k
R
C
V
R
C
V
Recommended values: 3 k
EXT
EXT
SS
SS
EXT
EXT
V
V
RC Oscillator
DD
DD
RA6
F
OSC
EXT
/4
RC OSCILLATOR MODE
OSC1
RCIO OSCILLATOR MODE
OSC1
OSC2/CLKO
EXT
I/O (OSC2)
values. The user also needs to
C
C
EXT
EXT
) and capacitor (C
> 20 pF
> 20 pF
R
R
EXT
EXT
PIC16F87/88
PIC16F87/88
100 k
100 k
Internal
Internal
Clock
Clock
EXT
) val-
4.5
The PIC16F87/88 devices include an internal oscillator
block which generates two different clock signals;
either can be used as the system’s clock source. This
can eliminate the need for external oscillator circuits on
the OSC1 and/or OSC2 pins.
The main output (INTOSC) is an 8 MHz clock source
which can be used to directly drive the system clock. It
also drives the INTOSC postscaler which can provide a
range of six clock frequencies from 125 kHz to 4 MHz.
The other clock source is the internal RC oscillator
(INTRC) which provides a 31.25 kHz (32 s nominal
period) output. The INTRC oscillator is enabled by
selecting the INTRC as the system clock source or
when any of the following are enabled:
• Power-up Timer
• Watchdog Timer
• Two-Speed Start-up
• Fail-Safe Clock Monitor
These features are discussed in greater detail in
Section 15.0 “Special Features of the CPU”.
The clock source frequency (INTOSC direct, INTRC
direct or INTOSC postscaler) is selected by configuring
the IRCF bits of the OSCCON register (page 40).
Note:
Internal Oscillator Block
Throughout this data sheet, when referring
specifically to a generic clock source, the
term “INTRC” may also be used to refer to
the clock modes using the internal oscillator
block. This is regardless of whether the
actual frequency used is INTOSC (8 MHz),
the
(31.25 kHz).
INTOSC
PIC16F87/88
postscaler
DS30487C-page 37
or
INTRC