PIC16F716 Microchip Technology, PIC16F716 Datasheet - Page 53

• Manufacturer Part Number: PIC16F716
• Description: 8-bit Flash-based Microcontroller with A/D Converter and Enhanced Capture/Compare/PWM
• Manufacturer: Microchip Technology

FIGURE 8-1:
8.1
For the A/D converter to meet its specified accuracy,
the charge holding capacitor (C
to fully charge to the input channel voltage level. The
analog input model is shown in Figure 8-2. The source
impedance (R
impedance directly affect the time required to charge
the capacitor C
impedance varies over the device voltage (V
source impedance affects the offset voltage at the
analog input (due to pin leakage current). The
maximum
sources is 10 k . After the analog input channel is
selected (changed) this acquisition must be done
before the conversion can be started.
FIGURE 8-2:
 2003 Microchip Technology Inc.
A/D Acquisition Requirements
Converter
recommended
S
A/D
) and the internal sampling switch (R
HOLD
Legend:
VA
. The sampling switch (R
A/D BLOCK DIAGRAM
ANALOG INPUT MODEL
Rs
impedance
C
V
I leakage
R
SS
C
ANx
PIN
T
IC
HOLD
C
5 pF
HOLD
PIN
(Reference
voltage)
V
REF
) must be allowed
= input capacitance
= threshold voltage
= leakage current at the pin due to
= interconnect resistance
= sampling switch
= sample/hold capacitance (from DAC)
various junctions
V
(Input voltage)
for
DD
PCFG2:PCFG0
V
DD
V
T
IN
= 0.6V
analog
). The
V
T
Preliminary
SS
SS
= 0.6V
)
)
V
DD
000 or
010 or
100 or
110 or 111
001 or
011 or
101
I leakage
± 500 nA
To calculate the minimum acquisition time, T
the
(DS33023). This equation calculates the acquisition
time to within 1/2 LSb error. The 1/2 LSb error is the
maximum error allowed for the A/D to meet its specified
accuracy.
R
Note:
IC
1k
PICmicro
CHS2:CHS0
V
SS R
DD
Sampling
Switch
When the conversion is started, the
holding capacitor is disconnected from the
input pin.
6V
5V
4V
3V
2V
®
SS
011
010
001
000
Mid-Range
Sampling Switch
5 6 7 8 9 10 11
V
SS
C
= DAC capacitance
= 51.2 pF
(k )
HOLD
PIC16F716
Reference
DS41206A-page 51
RA2/AN2
RA1/AN1
RA0/AN0
RA3/AN3/V
ACQ
Manual,
REF
, see