PIC16F688T-I/SL Microchip Technology, PIC16F688T-I/SL Datasheet - Page 75

• Manufacturer Part Number: PIC16F688T-I/SL
• Description: IC MCU PIC FLASH 4KX14 14SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F688T-I/SL

• Core Size: 8-Bit
• Program Memory Size: 7KB (4K x 14)
• Core Processor: PIC
• Speed: 20MHz
• Connectivity: UART/USART
• Peripherals: Brown-out Detect/Reset, POR, WDT
• Number Of I /o: 12
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Controller Family/series: PIC16F
• No. Of I/o's: 12
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 256Byte
• Cpu Speed: 20MHz
• No. Of Timers: 2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT14SO-1 - SOCKET TRANSITION 14SOIC 150/208AC162061 - HEADER INTRFC MPLAB ICD2 20PINAC162056 - HEADER INTERFACE ICD2 16F688
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: PIC16F688T-I/SL; PIC16F688T-I/SLTR

8.3
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 8-4. 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),
an A/D acquisition must be done before the conversion
EQUATION 8-1:
© 2009 Microchip Technology Inc.
Note 1: The reference voltage (V
The value for T
Solving for T
Therefore:
Assumptions:
2: The charge holding capacitor (C
3: The maximum recommended impedance for analog sources is 10 kΩ. This is required to meet the pin
A/D Acquisition Requirements
HOLD
T
leakage specification.
V
S
V
ACQ
V
T
) and the internal sampling switch (R
AP PLIE D
T
. The sampling switch (R
AP P LI ED
ACQ
AP P LIED
C
C
=
=
=
=
=
:
C
HOLD
=
=
=
2
ACQUISITION TIME EXAMPLE
Temperature
–
–
4.67
can be approximated with the following equations:
1.37
ΜS
10pF 1k
⎛
⎝
C
Amplifier Settling Time
T
2µs
⎛
⎜
⎝
⎛
⎜
⎝
1
) must be allowed to fully
AMP
HOLD
1 e
1 e
+
ΜS
µs
–
+
–
–
1.37
(
----------- -
2047
+
T
(
1
–
--------- -
R
C
–
-------- -
RC
RC
Ω
T
ΜS
DD
T
Tc
IC
+
C
C
+
⎞
⎠
⎞
⎟
⎠
⎞
⎟
⎠
), see Figure 8-4.
+
+
[
+
REF
(
7k
=
Temperature - 25°C
T
=
=
=
R
[
SS
(
Ω
COFF
) has no effect on the equation, since it cancels itself out.
SS
50°C- 25°C
) impedance
50°C and external impedance of 10k
V
V
V
+
+
CHOLD
CHOLD
A P PLIE D
HOLD
10k
R
S
) ln(1/2047)
+
Ω
) is not discharged after each conversion.
SS
)
Hold Capacitor Charging Time
ln(0.0004885)
)
) 0.05
⎛
⎝
(
1
–
) 0.05µs/°C
----------- -
2047
ΜS
(
1
/°C
can be started. To calculate the minimum acquisition
time, Equation 8-1 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.
⎞
⎠
)
]
;[2] V
;combining [1] and [2]
;[1] V
)
]
CHOLD
CHOLD
Ω
5.0V V
+
charged to within 1/2 lsb
charge response to V
Temperature Coefficient
DD
PIC16F688
DS41203E-page 73
APPLIED