PIC16F785-I/SO Microchip Technology, PIC16F785-I/SO Datasheet - Page 26

• Manufacturer Part Number: PIC16F785-I/SO
• Description: IC PIC MCU FLASH 2KX14 20SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F785-I/SO

• Program Memory Type: FLASH
• Program Memory Size: 3.5KB (2K x 14)
• Package / Case: 20-SOIC (7.5mm Width)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 17
• Eeprom Size: 256 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 128 B
• Interface Type: RS- 232/USB
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 17
• Number Of Timers: 3
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DV164120, DM163029
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 14-ch x 10-bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT20SO1-1 - SOCKET TRANS ICE 20DIP TO 20SOICXLT18SO-1 - SOCKET TRANSITION 18SOIC 300MILAC162060 - HEADER INTRFC MPLAB ICD2 20PINAC164039 - MODULE SKT PROMATE II 20DIP/SOIC
• Connectivity: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC16F785
3.2
Clock source modes can be classified as external or
internal.
• External clock modes rely on external circuitry for
• Internal clock sources are contained internally
The system clock can be selected between external or
internal clock sources via the System Clock Selection
(SCS) bit (see Section 3.5 “Clock Switching”).
TABLE 3-1:
3.3.2
The External Clock (EC) mode allows an externally
generated logic level as the system clock source.
When operating in this mode, an external clock source
is connected to OSC1 pin and the RA4 pin is available
for general purpose I/O. Figure 3-2 shows the pin
connections for EC mode.
The Oscillator Start-up Timer (OST) is disabled when
EC mode is selected. Therefore, there is no delay in
operation after a Power-on Reset (POR) or wake-up
from Sleep. Because the PIC16F785 design is fully
static, stopping the external clock input will have the
effect of halting the device while leaving all data intact.
Upon restarting the external clock, the device will
resume operation as if no time had elapsed.
DS41249A-page 24
Note 1:
Switch From
the clock source. Examples are oscillator modules
(EC mode), quartz crystal resonators or ceramic
resonators (LP, XT, and HS modes), and
resistor-capacitor (RC mode) circuits.
within the PIC16F785. The PIC16F785 has two
internal oscillators; the 8 MHz High-frequency
Internal Oscillator (HFINTOSC) and 31 kHz
Low-frequency Internal Oscillator (LFINTOSC).
Sleep/POR
LFINTOSC
Sleep/POR
LFINTOSC
(31 kHz)
(31 kHz)
Sleep
Clock Source Modes
The 5 µs–10 µs start-up delay is based on a 1 MHz System Clock.
EC MODE
LP, XT, HS
Switch To
OSCILLATOR DELAY EXAMPLES
INTOSC
INTOSC
EC, RC
EC, RC
INTRC
125 kHz–8 MHz
31 kHz–20 MHz
125 kHz–8 MHz
DC – 20 MHz
DC – 20 MHz
Frequency
31 kHz
Preliminary
5 µs–10 µs (approx.)
1024 Clock Cycles
Oscillator Delay
CPU Start-up
1 µs (approx.)
(OST)
3.3
3.3.1
When the PIC16F785 is configured for any of the
crystal oscillator modes (LP, XT or HS), the Oscillator
Start-up Timer (OST) is enabled, which extends the
reset period to allow the oscillator additional time to
stabilize. The OST counts 1024 clock periods present
on the OSC1 pin following a Power-on Reset (POR), a
wake from Sleep, or when the Power-up Timer (PWRT)
has expired (if the PWRT is enabled). During this time,
the program counter does not increment and program
execution is suspended. The OST ensures that the
oscillator circuit, using a quartz crystal resonator or
ceramic resonator, has started and is providing a stable
system clock to the PIC16F785. Table 3-1 shows
examples where the oscillator delay is invoked.
In order to minimize latency between external oscillator
start-up and code execution, the Two-speed Clock
Start-up mode can be selected (see Section 3.6
“Two-Speed Clock Start-up Mode”).
FIGURE 3-2:
Clock from
Ext. System
(1)
External Clock Modes
OSCILLATOR START-UP TIMER (OST)
Following a wake-up from Sleep mode or POR,
CPU start-up is invoked to allow the CPU to
become ready for code execution.
RA4
EXTERNAL CLOCK (EC)
MODE OPERATION
 2004 Microchip Technology Inc.
Comments
OSC1/CLKIN
I/O (OSC2)
PIC16F785