PIC16F690DM-PCTLHS Microchip Technology, PIC16F690DM-PCTLHS Datasheet - Page 118

• Manufacturer Part Number: PIC16F690DM-PCTLHS
• Description: BOARD DEMO PICTAIL HUMIDITY SNSR
• Manufacturer: Microchip Technology
• Series: PICtail™r

Specifications of PIC16F690DM-PCTLHS

• Sensor Type: Humidity
• Sensing Range: 1 ~ 99% RH
• Interface: Analog
• Voltage - Supply: 5V
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: MCP6291, PIC16F690
• Processor To Be Evaluated: MCP6291 and PIC16F690
• Interface Type: ICSP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AC162061 - HEADER INTRFC MPLAB ICD2 20PIN
• Sensitivity: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

PIC16F631/677/685/687/689/690
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:
DS41262E-page 116
The value for T
Solving for T
Therefore:
Assumptions:
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
HOLD
T
S
ACQ
T
) and the internal sampling switch (R
T
C
. The sampling switch (R
ACQ
:
C
C
⎛
⎝
⎛
⎜
⎝
⎛
⎜
⎝
Temperature
can be approximated with the following equations:
=
=
=
=
=
1
1 e
1 e
HOLD
=
=
=
ACQUISITION TIME EXAMPLE
–
2μ
–
4.67μ
–
–
–
1.37
C
10pF 1k
Amplifier Settling Time
T
2μs
--------------------------
(
S
) must be allowed to fully
AMP
HOLD
2
–
--------- -
–
-------- -
RC
RC
+
μs
T
Tc
n
S
+
C
1.37μ
+
(
⎞
⎟
⎠
⎞
⎟
⎠
+
1
T
(
1
R
C
) 1
=
=
Ω
T
DD
IC
+
C
–
=
S
+
V
), see Figure 9-4.
V
+
+
+
[
(
7k
A PP LIE D
⎞
⎠
CHOLD
50°C and external impedance of 10k
Temperature - 25°C
T
R
[
SS
(
Ω
COFF
SS
50°C- 25°C
=
) impedance
+
+
V
10k
R
CHOLD
⎛
⎝
S
1
) ln(1/2047)
+
Ω
SS
–
)
Hold Capacitor Charging Time
ln(0.0004885)
)
) 0.05μ
--------------------------
(
(
2
n
+
) 0.05μs/°C
1
1
(
S
) 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.
–
)
]
⎞
⎠
;[1] V
;[2] V
;combining [1] and [2]
)
]
Ω
CHOLD
CHOLD
5.0V V
+
charged to within 1/2 lsb
charge response to V
DD
Temperature Coefficient
© 2008 Microchip Technology Inc.
APPLIED