PIC16F877-20/P Microchip Technology, PIC16F877-20/P Datasheet - Page 452

• Manufacturer Part Number: PIC16F877-20/P
• Description: IC MCU FLASH 8KX14 EE 40DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F877-20/P

• Core Size: 8-Bit
• Program Memory Size: 14KB (8K x 14)
• Core Processor: PIC
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 33
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Controller Family/series: PIC16F
• No. Of I/o's: 33
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 368Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 444-1001 - DEMO BOARD FOR PICMICRO MCU
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

PICmicro MID-RANGE MCU FAMILY
24.3.7
DS31024A-page 24-10
Slope A/D Resolution, Speed, Voltage Range, and Capacitor Selection
The Slope A/D module allows many trade-offs. For a conversion the user needs to make the fol-
lowing Trade-offs:
• The Resolution of the Result
• The Speed of the Conversion
• The Analog Input Voltage Range
• The External Capacitor
The resolution is the number of bits that is used by the ADTMR to represent the measured input
voltage. This resolution affects the time that the conversion can be completed in.
shows the trade-off between the resolution of the conversion and the maximum conversion time.
The conversion time for the Slope A/D converter can be calculated using the equation:
Therefore at 4 MHz, the conversion time for 16 bits is 16.384 msec. Conversely, it is 256 sec for
10-bits.
Table 24-1: ADTMR Initialization Values and Conversion Times
Resolution
Conversion Time = (1/Fosc) x 2
Where Fosc is the oscillator frequency and N is the number of bits of resolution desired.
Bits
.
16
15
14
13
12
11
10
Value Loaded
into ADTMR
C000h
E000h
FC00h
0000h
8000h
F000h
F800h
65536 T
32768 T
16384 T
N
8192 T
4096 T
2048 T
1024 T
Cycles
OSC
OSC
OSC
OSC
OSC
OSC
OSC
Maximum Conversion Time
204.8 s
102.4 s
3.28 ms
1.64 ms
20 MHz
51.2 s
820 s
410 s
1997 Microchip Technology Inc.
16.38 ms
2.05 ms
1.03 ms
8.2 ms
4.1 ms
500 s
250 s
4 MHz
Table 24-1