pic32mx320f064h Microchip Technology Inc., pic32mx320f064h Datasheet - Page 448

• Manufacturer Part Number: pic32mx320f064h
• Description: 64/100-pin General Purpose, 32-bit Flash Microcontrollers
• Manufacturer: Microchip Technology Inc.

PIC32MX FAMILY
22.6.2
The analog input model of the 10-bit A/D converter is
shown in Figure 22-3. The total acquisition time for the
A/D conversion is a function of the internal amplifier
settling time and the holding capacitor charge time.
For the A/D converter to meet its specified accuracy,
the charge holding capacitor (C
to fully charge to the voltage level on the analog input
pin. The analog output source impedance (R
interconnect impedance (R
pling switch (R
the time required to charge the C
impedance of the analog sources must therefore be
small enough to fully charge the holding capacitor
FIGURE 22-3:
DS61143A-page 446
C
R
R
I
Legend:
LEAKAGE
Note: C
PIN
SS
S
= source resistance
= sampling switch resistance
= input capacitance
PIN
ADC SAMPLING REQUIREMENTS
= leakage current at the pin due to various junctions
value depends on device package and is not tested. Effect of C
SS
) impedance combine to directly affect
VA
Rs
10-BIT A/D CONVERTER ANALOG INPUT MODEL
ANx
C
IC
PIN
) and the internal sam-
HOLD
HOLD
) must be allowed
. The combined
V
V
R
C
DD
Advance Information
T
V
IC
HOLD
V
T
= threshold voltage
T
= interconnect resistance
S
= 0.6V
= 0.6V
), the
= sample/hold capacitance (from DAC)
R
I
± 500 nA
LEAKAGE
IC
≤ 250Ω
within the chosen sample time. To minimize the effects
of pin leakage currents on the accuracy of the A/D con-
verter, the maximum recommended source imped-
ance, R
ksps and a maximum of 500Ω for conversion rates of
up to 400 ksps). After the analog input channel is
selected (changed), this acquisition function must be
completed prior to starting the conversion. The internal
holding capacitor will be in a discharged state prior to
each sample operation.
At least 1 T
conversions for the acquisition time. For more details,
see the device electrical specifications.
PIN
Sampling
Switch
S
, is 5 kΩ for the conversion rates of up to 300
negligible if Rs ≤ 5 kΩ.
R
AD
SS
time period should be allowed between
R
V
SS
SS
C
= DAC Capacitance
= 4.4 pF
≤ 3 kΩ
HOLD
© 2007 Microchip Technology Inc.