PIC16F884-E/P Microchip Technology, PIC16F884-E/P Datasheet - Page 109

• Manufacturer Part Number: PIC16F884-E/P
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,DIP,40PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F884-E/P

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 35
• Program Memory Size: 7KB (4K x 14)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: DVA18XP400 - DEVICE ADAPTER 18F4220 PDIP 40LD
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9.3
For the ADC to meet its specified accuracy, the charge
holding capacitor (C
charge to the input channel voltage level. The Analog
Input model is shown in Figure 9-4. The source
impedance (R
impedance directly affect the time required to charge the
capacitor C
varies over the device voltage (V
The maximum recommended impedance for analog
sources is 10 kΩ. As the source impedance is
decreased, the acquisition time may be decreased.
After the analog input channel is selected (or changed),
EQUATION 9-1:
© 2009 Microchip Technology Inc.
Note 1: The reference voltage (V
The value for T
Solving for T
Therefore:
Assumptions:
V
V
V
2: The charge holding capacitor (C
3: The maximum recommended impedance for analog sources is 10 kΩ. This is required to meet the pin
A/D Acquisition Requirements
AP PLIE D
AP P LI ED
AP P LIED
HOLD
T
leakage specification.
S
ACQ
T
) and the internal sampling switch (R
T
. The sampling switch (R
ACQ
C
⎛
⎝
C
⎛
⎜
⎝
⎛
⎜
⎝
=
=
=
1
=
=
:
1 e
1 e
C
HOLD
=
=
=
–
2
ACQUISITION TIME EXAMPLE
Temperature
–
–
4.67
–
can be approximated with the following equations:
–
1.37
ΜS
10pF 1k
--------------------------
(
C
Amplifier Settling Time
T
2µs
2
) must be allowed to fully
AMP
HOLD
–
--------- -
–
-------- -
RC
+
n
RC
ΜS
µs
T
Tc
+
+
C
1.37
(
1
⎞
⎟
⎠
⎞
⎟
⎠
1
+
T
(
) 1
R
C
=
=
Ω
T
ΜS
DD
–
IC
+
C
+
), see Figure 9-4.
V
V
+
+
[
+
REF
⎞
⎠
(
7k
=
CHOLD
A P PLIE D
Temperature - 25°C
T
R
[
SS
(
Ω
COFF
=
) has no effect on the equation, since it cancels itself out.
SS
50°C- 25°C
) impedance
50°C and external impedance of 10k
+
+
V
HOLD
10k
CHOLD
R
PIC16F882/883/884/886/887
S
⎛
⎝
) ln(1/2047)
+
1
Ω
) is not discharged after each conversion.
SS
)
Hold Capacitor Charging Time
–
ln(0.0004885)
)
) 0.05
--------------------------
(
(
2
n
+
) 0.05µs/°C
1
ΜS
1
(
) 1
/°C
an A/D acquisition must be done before the conversion
can be started. To calculate the minimum acquisition
time, Equation 9-1 may be used. This equation
assumes that 1/2 LSb error is used (1024 steps for the
ADC). The 1/2 LSb error is the maximum error allowed
for the ADC to meet its specified resolution.
–
)
⎞
⎠
]
;[2] V
;combining [1] and [2]
;[1] V
)
]
CHOLD
CHOLD
Ω
5.0V V
+
charge response to V
charged to within 1/2 lsb
Temperature Coefficient
DD
DS41291F-page 107
APPLIED