參數(shù)資料
型號(hào): 16F630
廠商: Microchip Technology Inc.
英文描述: 14-Pin FLASH-Based 8-Bit CMOS Microcontrollers
中文描述: 14引腳基于閃存的8位CMOS微控制器
文件頁數(shù): 49/132頁
文件大小: 2651K
代理商: 16F630
2003 Microchip Technology Inc.
DS40039C-page 47
PIC16F630/676
7.2
A/D Acquisition Requirements
For the A/D converter to meet its specified accuracy,
the charge holding capacitor (C
HOLD
) must be allowed
to fully charge to the input channel voltage level. The
analog input model is shown in Figure 7-3. The source
impedance (R
S
) and the internal sampling switch (R
SS
)
impedance directly affect the time required to charge
the capacitor C
HOLD
. The sampling switch (R
SS
)
impedance varies over the device voltage (V
DD
), see
Figure 7-3.
The maximum recommended imped-
ance for analog sources is 10 k
.
As the impedance
is decreased, the acquisition time may be decreased.
After the analog input channel is selected (changed),
this acquisition must be done before the conversion
can be started.
To calculate the minimum acquisition time, Equation 7-1
may be used. This equation assumes that 1/2 LSb error
is used (1024 steps for the A/D). The 1/2 LSb error is the
maximum error allowed for the A/D to meet its specified
resolution.
To calculate the minimum acquisition time, T
ACQ
, see
the
PICmicro
Mid-Range
(DS33023).
Reference
Manual
EQUATION 7-1:
ACQUISITION TIME
FIGURE 7-3:
ANALOG INPUT MODEL
T
ACQ
T
C
T
ACQ
=
=
=
=
=
=
=
=
Amplifier Settling Time +
Hold Capacitor Charging Time +
Temperature Coefficient
T
AMP
+ T
C
+ T
COFF
2
μ
s + T
C
+ [(Temperature -25
°
C)(0.05
μ
s/°C)]
C
HOLD
(R
IC
+ R
SS
+ R
S
) In(1/2047)
- 120pF (1k
+ 7k
+ 10k
) In(0.0004885)
16.47
μ
s
2
μ
s + 16.47
μ
s + [(50°C -25
°
C)(0.05
μ
s/
°
C)
19.72
μ
s
Note 1:
The reference voltage (V
REF
) has no effect on the equation, since it cancels itself out.
2:
The charge holding capacitor (C
HOLD
) is not discharged after each conversion.
3:
The maximum recommended impedance for analog sources is 10 k
. This is required to meet the pin
leakage specification.
C
PIN
5 pF
VA
R
S
ANx
V
DD
V
T
= 0.6V
V
T
= 0.6V
I
LEAKAGE
± 500 nA
R
IC
1K
Sampling
Switch
SS R
SS
C
HOLD
= DAC capacitance
= 120 pF
V
SS
6V
5V
4V
3V
2V
Sampling Switch
(k
)
5 6 7 8 91011
V
DD
Legend
C
PIN
V
T
I
LEAKAGE
R
IC
SS
C
HOLD
= input capacitance
= threshold voltage
= leakage current at the pin due to
various junctions
= interconnect resistance
= sampling switch
= sample/hold capacitance (from DAC)
相關(guān)PDF資料
PDF描述
16F84 CAT 5E CROSSOVER, BLUE 15 FT PATCH CABLE
16F84A CAT 5E CROSSOVER PATCH CORD CABLE BLUE 20 FT
16F871 CAT 5E CROSSOVER PATCH CORD CABLE GREEN 6 FT
16F872 CAT 5E CROSSOVER PATCH CORD CABLE GREEN 10 FT
16F876A 28/40-pin Enhanced FLASH Microcontrollers
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
16F684-I 制造商:Microchip Technology Inc 功能描述:
16F6H 制造商:EDAL 制造商全稱:EDAL 功能描述:Silicon High Voltage Assembly
16F6H1 制造商:EDAL 制造商全稱:EDAL 功能描述:Silicon High Voltage Assembly
16F7674 制造商:未知廠家 制造商全稱:未知廠家 功能描述:SMD TWEEZER HEAD
16F7676 制造商:未知廠家 制造商全稱:未知廠家 功能描述:CLIP KABELKIT