PIC16F818-I/P Microchip Technology, PIC16F818-I/P Datasheet - Page 415

• Manufacturer Part Number: PIC16F818-I/P
• Description: IC MCU FLASH 1KX14 18-DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F818-I/P

• Program Memory Type: FLASH
• Program Memory Size: 1.75KB (1K x 14)
• Package / Case: 18-DIP (0.300", 7.62mm)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 5x10b
• 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: I2C/SPI/SSP
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 16
• Number Of Timers: 3
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DM163014
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 5-ch x 10-bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: ACICE0202 - ADAPTER MPLABICE 18P 300 MILAC164010 - MODULE SKT PROMATEII DIP/SOIC
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

22.6.1
1997 Microchip Technology Inc.
Faster Conversion - Lower Resolution Trade-off
Section 22. Basic 8-bit A/D Converter
Not all applications require a result with 8-bits of resolution, but may instead require a faster con-
version time. The A/D module allows users to make the trade-off of conversion speed to resolu-
tion. Regardless of the resolution required, the acquisition time is the same. To speed up the
conversion, the clock source of the A/D module may be switched so that the T
the minimum specified time (see the applicable electrical specification). Once the T
lates the minimum specified time, all the following A/D result bits are not valid (see A/D Conver-
sion Timing in the Electrical Specifications section.) The clock sources may only be switched
between the three oscillator versions (cannot be switched from/to RC). The equation to deter-
mine the time before the oscillator can be switched is as follows:
Since the T
ware loop, etc.) to determine when the A/D oscillator may be changed.
comparison of time required for a conversion with 4-bits of resolution, versus the 8-bit resolution
conversion. The example is for devices operating at 20 MHz and 16 MHz (The A/D clock is pro-
grammed for 32T
for 2T
The 2T
values.
Example 22-3:
Note 1: The PIC16C71 has a minimum T
T
T
T
AD
OSC
AD
Conversion time = T
Where:
OSC
+ N • T
2: If the full 8-bit conversion is required, the A/D clock source should not be changed.
OSC
.
All other devices have a minimum T
AD
violates the minimum T
AD
is based from the device oscillator, the user must use some method (a timer, soft-
+ (10 - N)(2T
OSC
4-bit vs. 8-bit Conversion Times
N = number of bits of resolution required.
), and assumes that immediately after 5T
AD
+ N • T
OSC
)
AD
AD
+ (10 - N)(2T
time since the last 4-bits will not be converted to correct
AD
(MHz)
AD
time of 2.0 s.
Freq.
20
16
20
16
20
16
time of 1.6 s.
(1)
OSC
)
10.75 s
AD
62.5 ns
1.6 s
2.0 s
8.6 s
50 ns
4-bit
, the A/D clock is programmed
Resolution
Example 22-3
DS31022A-page 22-13
AD
62.5 ns
17.6 s
time violates
1.6 s
2.0 s
50 ns
22 s
8-bit
AD
time vio-
shows a
22