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參數(shù)資料
| 型號： | TC835 |
| 廠商： | TelCom Semiconductor, Inc. |
| 英文描述： | PERSONAL COMPUTER DATA ACQUISITION A/D CONVERTER |
| 中文描述： | 個人計算機數(shù)據(jù)采集的A / D轉(zhuǎn)換器 |
| 文件頁數(shù)： | 9/12頁 |
| 文件大?。?/td> | 206K |
| 代理商： | TC835 |
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TELCOM SEMICONDUCTOR, INC.
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TC835
PERSONAL COMPUTER
DATA ACQUISITION A/D CONVERTER
The stability of the reference voltage is a major factor in
the overall absolute accuracy of the converter. For this
reason, it is recommended that a high-quality reference be
used where high-accuracy absolute measurements are
being made. Suitable references are:
Part Type
Manufacturer
TC04A
TC9491
TelCom Semiconductor
TelCom Semiconductor
APPLICATIONS INFORMATION
Component Value Selection
The integrating resistor is determined by the full-scale
input voltage and the output current of the buffer used to
charge the integrator capacitor. Both the buffer amplifier and
the integrator have a class A output stage, with 100
μ
A of
quiescent current. A 20
μ
A drive current gives negligible
linearity errors. Values of 5
μ
A to 40
μ
A give good results.
The exact value of an integrating resistor for a 20
μ
A current
is easily calculated.
R
INT
=
Integrating Capacitor
The product of integrating resistor and capacitor should
be selected to give the maximum voltage swing that ensures
the tolerance buildup will not saturate the integrator swing
(approximately 0.3V from either supply). For
±
5V supplies
and ANALOG COMMON tied to supply ground, a
±
3.5V to
±
4V full-scale integrator swing is adequate. A 0.10
μ
F to 0.47
μ
F is recommended. In general, the value of C
INT
is given by:
[10,000
×
clock period]
×
I
INT
Integrator output voltage swing
C
INT
=
=
(10,000) (clock period) (20
μ
A)
Integrator output voltage swing
A very important characteristic of the integrating capaci-
tor is that it has low dielectric absorption to prevent rollover
or ratiometric errors. A good test for dielectric absorption is
to use the capacitor with the input tied to the reference. This
ratiometric condition should read half-scale 0.9999, any
deviation is probably due to dielectric absorption. Polypro-
pylene capacitors give undetectable errors at reasonable
cost. Polystyrene and polycarbonate capacitors may also be
used in less critical applications.
Auto-Zero and Reference Capacitors
The size of the auto-zero capacitor has some influence
on the noise of the system. A large capacitor reduces the
noise. The reference capacitor should be large enough such
that stray capacitance to ground from its nodes is negligible.
The dielectric absorption of the reference capacitor and
auto-zero capacitor are only important at power-on, or when
the circuit is recovering from an overload. Smaller or cheaper
capacitors can be used if accurate readings are not required
for the first few seconds of recovery.
Reference Voltage
The analog input required to generate a full-scale output
is V
IN
= 2 V
REF
.
Conversion Timing
Line Frequency Rejection
A signal integration period at a multiple of the 60 Hz line
frequency will maximize 60 Hz "line noise" rejection.
A 200 kHz clock frequency will reject 60 Hz and 400 Hz
noise. This corresponds to five readings per second.
full-scale voltage
20
μ
A
Conversion Rate vs Clock Frequency
Oscillator Frequency
(kHz)
Conversion Rate
(Conv/Sec)
100
120
200
300
400
800
1200
2.5
3
5
7.5
10
20
30
Oscillator Frequency
(kHz)
60 Hz
50 Hz
400 Hz
50.000
53.333
66.667
80.000
83.333
100.000
125.000
133.333
166.667
200.000
250.000
—
—
—
—
—
—
—
—
—
—
—
—
—
The conversion rate is easily calculated:
Conversion Rate
(Readings 1/sec) =
Line Frequency Rejection
Clock Frequency (Hz)
4000
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| TC835CBU713 | 功能描述:LED顯示驅(qū)動器 4.5 D BCD A/D-PC Dat RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube |
| TC835CKW | 功能描述:LED顯示驅(qū)動器 4.5 D BCD A/D-PC Dat RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube |
| TC835CKW713 | 功能描述:LED顯示驅(qū)動器 4.5 D BCD A/D-PC Dat RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube |
| TC835CPI | 功能描述:LED顯示驅(qū)動器 4.5 D BCD A/D-PC Dat RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube |
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