PIC18F43K22T-I/ML Microchip Technology Inc., PIC18F43K22T-I/ML Datasheet - Page 302

• Manufacturer Part Number: PIC18F43K22T-I/ML
• Description: 8KB, FLASH, 3968BYTES-RAM, 8-BIT FAMILY, NANOWATT XLP, 44 QFN 8X8X0.9MM T/R
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F43K22T-I/ML

• A/d Inputs: 28-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 16 MIPS
• Eeprom Memory: 1K Bytes
• Input Output: 35
• Interface: I2C/SPI/UART/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin QFN
• Programmable Memory: 8K Bytes
• Ram Size: 512 Bytes
• Speed: 48 MHz
• Temperature Range: –40 to 125 °C
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 1.8-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part

PIC18(L)F2X/4XK22
17.3
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
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 k. As the source impedance is
decreased, the acquisition time may be decreased.
After the analog input channel is selected (or changed),
EQUATION 17-1:
DS41412D-page 302
Note 1: The reference voltage (V
Assumptions:
The value for T
Solving for T
Therefore:
2: The charge holding capacitor (C
3: The maximum recommended impedance for analog sources is 10 k. This is required to meet the pin
A/D Acquisition Requirements
HOLD
leakage specification.
T
V
S
V
V
ACQ
T
) and the internal sampling switch (R
AP PLIE D
T
. The sampling switch (R
ACQ
AP P LI ED
AP P LIED
C
C
=
=
=
=
=
:
C
HOLD
=
=
=
–
ACQUISITION TIME EXAMPLE
Temperature
5µs
–
7.45µs
can be approximated with the following equations:
1.20
13.5pF 1k


C
Amplifier Settling Time
T
5µs






1
) must be allowed to fully
AMP
HOLD
1 e
1 e
+
µs
–
Figure
–
+
–
1.20µs
----------- -
2047

+
T

R
1
–
--------- -
C
–
-------- -
RC
DD
RC
T
T
Tc
IC

+
C
C
17-5. The source
), see








+
+
+
+
REF


=
T
Temperature - 25°C
=
=
=
R
700

SS

) has no effect on the equation, since it cancels itself out.
COFF
SS
50°C- 25°C
50°C and external impedance of 10k
) impedance
Figure
V
V
V

+
CHOLD
CHOLD
A P PLIE D
HOLD
+
R
S
10k
17-5.
 ln(1/2047)
+
) is discharged after each conversion.
Preliminary
SS
Hold Capacitor Charging Time

)
 0.05 




1
ln(0.0004885)
–
 0.05µs/°C
----------- -
2047

s/
1
an A/D acquisition must be done before the conversion
can be started. To calculate the minimum acquisition
time,
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.
°C




Equation 17-1
;[2] V
;combining [1] and [2]
;[1] V


CHOLD
CHOLD

3.0V V
+
charge response to V
charged to within 1/2 lsb
may be used. This equation
Temperature Coefficient
 2010 Microchip Technology Inc.
DD
APPLIED