PIC16F877-20/P Microchip Technology, PIC16F877-20/P Datasheet - Page 429

• 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

1997 Microchip Technology Inc.
Legend C
V
AIN
Rs
V
I
R
SS
C
LEAKAGE
T
PIN
IC
HOLD
ANx
C
5 pF
Now to get an idea what happens to the acquisition time when the source impedance is a mini-
mal value ( R
the source impedance made a minimal value ( R
Example 23-2:
Figure 23-3: Analog Input Model
PIN
T
Temperature coefficient is only required for temperatures > 25 C.
T
T
T
ACQ
ACQ
C
ACQ
= input capacitance
= threshold voltage
= leakage current at the pin due to
= interconnect resistance
= sampling switch
= sample/hold capacitance (from DAC)
Note 1: The reference voltage (V
Note 2: The charge holding capacitor (C
Note 3: The maximum recommended impedance for analog sources is 10 k . This is
Note 4: After a conversion has completed, a 2.0T
=
various junctions
=
=
=
Section 23. 10-bit A/D Converter
out.
required to meet the pin leakage specification.
can begin again. During this time the holding capacitor is not connected to the
selected A/D input channel.
S
T
2 s + Tc + [(Temp - 25 C)(0.05 s/ C)]
-C
-120 pF (1 k + 7 k + 50 ) ln(0.0004885)
-120 pF (8050 ) ln(0.0004885)
-0.966 s (-7.6241)
7.36 s
2 s + 16.47 s + [(50 C - 25 C)(0.05 s/ C)]
9.36 s + 1.25 s
10.61 s
= 50
AMP
V
HOLD
DD
Calculating the Minimum Required Acquisition Time (Case 2)
V
+ T
V
).
T
T
(R
Example 23-2
= 0.6V
= 0.6V
C
IC
+ T
+ R
Preliminary
COFF
SS
+ R
I leakage
100 nA
REF
shows the same conditions as in
S
R
) ln(1/2047)
IC
) has no effect on the equation, since it cancels itself
HOLD
1k
S
V
) is not discharged after each conversion.
= 50 ).
SS
DD
Sampling
Switch
AD
6V
5V
4V
3V
2V
R
delay must complete before acquisition
SS
Sampling Switch
5 6 7 8 9 10 11
V
SS
C
( k )
HOLD
Example 23-1
= 120 pF
DS31023A-page 23-7
with only
23