PIC16F721T-I/ML Microchip Technology, PIC16F721T-I/ML Datasheet - Page 83

• Manufacturer Part Number: PIC16F721T-I/ML
• Description: 7 KB FLASH, 256 B SRAM, 18 I/O 20 QFN 4x4mm T/R
• Manufacturer: Microchip Technology
• Series: PIC® XLP™ 16Fr

Specifications of PIC16F721T-I/ML

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 17
• Program Memory Size: 7KB (4K x 14)
• Program Memory Type: FLASH
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 12x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• 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
impedance (R
impedance directly affect the time required to charge
the capacitor C
impedance varies over the device voltage (V
to
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
EQUATION 9-1:
 2010 Microchip Technology Inc.
The value for T
Solving for T
Assumptions:
Therefore:
Figure
Note: TCOFF is zero for temperatures below 25 degrees C.
V
V
V
Note: Where n = number of bits of the ADC.
A/D Acquisition Requirements
AP P LI ED
AP P LI ED
AP P LI ED
9-3.
T
S
ACQ
T
) and the internal sampling switch (R
C
ACQ
T
:
HOLD
C
C
The








Temperature
=
can be approximated with the following equations:
=
=
=
=
1
1 e
1 e
HOLD
=
=
=
. The sampling switch (R
ACQUISITION TIME EXAMPLE
2µs
–
–
–
2.25
–
–
5.5µs
Amplifier Settling Time
T
2µs
C
20pF 1k
maximum
--------------------------

AMP
) must be allowed to fully
2
–
--------- -
–
-------- -
HOLD
RC
RC
+
µs
T
Tc
n
+
Figure
C
2.25µs
+







+
T
1
1

C
 1
=
R
=
T

+
–
IC
C
=
9-3. The source
V
V
+
+
+

+

A PP LIE D
CHOLD


recommended
7k
50°C and external impedance of 10k
Temperature - 25°C
T

R

COFF

50°C- 25°C
=
SS
+
+
DD
V
10k
R
CHOLD
), refer


S
+
1
 ln(1/511)

SS
SS
–
Hold Capacitor Charging Time

)
)
 0.05µs/°C
--------------------------

ln(0.001957)

2
n
+
 0.05µs/°C
1
1

 1
selected (or changed), an A/D acquisition must be
done before the conversion can be started. To calculate
the minimum acquisition time,
used. This equation assumes that 1/2 LSb error is used
(256 steps for the ADC). The 1/2 LSb error is the
maximum error allowed for the ADC to meet its
specified resolution. It is noted that if the device is
operated at or below 2.0V V
selected for the ADC and if the analog input changes
by more than 1 or 2 LSBs from the previous
conversion, then the use of at least 16 s T
recommended.
–




PIC16F/LF720/721
;[1] V
;[2] V
;combining [1] and [2]



CHOLD
CHOLD
5.0V V
+
charged to within 1/2 lsb
charge response to V
DD
Temperature Coefficient
DD
Equation 9-1
with the FRC clock
DS41430A-page 83
APPLIED
ACQ
may be
time is