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參數(shù)資料
| 型號： | TC820 |
| 廠商： | TelCom Semiconductor, Inc. |
| 元件分類： | 通用總線功能 |
| 英文描述： | 3-3/4 DIGIT A/D CONVERTER WITH FREQUENCY COUNTER AND LOGIC PROBE |
| 中文描述： | 3-3/4數(shù)字A / D轉(zhuǎn)換頻率計數(shù)器和邏輯探針轉(zhuǎn)爐 |
| 文件頁數(shù)： | 18/22頁 |
| 文件大?。?/td> | 275K |
| 代理商： | TC820 |
3-166
TELCOM SEMICONDUCTOR, INC.
3-3/4 A/D CONVERTER WITH
FREQUENCY COUNTER
AND LOGIC PROBE
TC820
Figure 17. System Clock Generation
nominal
±
2V integrator swing. An exact expression for C
INT
is:
C
INT
=
where: f
OSC
= Clock frequency
V
FS
= Full-scale input voltage
R
INT
= Integrating resistor
V
INT
= Desired full-scale integrator output swing
C
INT
must have low dielectric absorption to minimize
roll-over error. A polypropylene capacitor is recommended.
Integrating Resistor — R
INT
The input buffer amplifier and integrator are designed
with class A output stages. The integrator and buffer can
supply 40
μ
A drive currents with negligible linearity errors.
R
INT
is chosen to remain in the output stage linear drive
region but not so large that printed circuit board leakage
currents induce errors. For a 400mV full scale, R
INT
should
be about 100k
.
Reference Voltage Selection
A full-scale reading (4000 counts for TC820) requires
the input signal be twice the reference voltage.
Table III. Reference Voltage Selection
Full-Scale
Input Voltage
(V
FS
) (Note 1)
V
REF
Resolution
200mV
Note 2
–
400mV
1V
2V
(Notes 3, 4)
200mV
500mV
1V
10
μ
V
250
μ
V
500
μ
V
NOTES:
1. TC820 in A/D converter mode, RANGE/FREQ = logic low.
2. Not recommended.
3. V
FS
> 2V may exceed the input common mode range.
See "10:1 Range Change" section.
4. Full-scale voltage values are not limited to the values
shown. For example, TC820 V
FS
can be any value from
400mV to 2V.
In some applications, a scale factor other than unity may
exist between a transducer output voltage and the required
digital reading. Assume, for example, that a pressure trans-
ducer output is 800mV for 4000 lb/in
2
. Rather than dividing
the input voltage by two, the reference voltage should be set
to 400mV. This permits the transducer input to be used
directly.
The internal voltage reference potential available at
analog common will normally be used to supply the
converter's reference voltage. This potential is stable when-
ever the supply potential is greater than approximately 7V.
The low-battery detection circuit and analog common oper-
ate from the same internal reference. This ensures that the
low-battery annunciator will turn on at the time the internal
reference begins to lose regulation.
The TC820 can also operate with an external reference.
Figure 18 shows internal and external reference applica-
tions.
Ratiometric Resistance Measurements
The TC820 true differential input and differential refer-
ence make ratiometric readings possible. In ratiometric
operation, an unknown resistance is measured with respect
to a known standard resistance. No accurately defined
reference voltage is needed.
The unknown resistance is put in series with a known
standard and a current is passed through the pair (Fig-
ure 19). The voltage developed across the unknown is
applied to the input and voltages across the known resistor
A/D
COUNTER
TC820
÷
40,000
COUNTER
TIME BASE
÷
240
LCD
BACKPLANE
DRIVER
÷
8
BUZZER
÷
2
OSC1
OSC2
OSC3
XTAL
OSCILLATOR
COMPONENTS
R/C
OSCILLATOR
COMPONENTS
4000 V
FS
V
INT
R
INT
f
OSC
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參數(shù)描述 |
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| TC820CKW | 功能描述:LCD 驅(qū)動器 3-3/4 A/D Converter RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| TC820CKW713 | 功能描述:LCD 驅(qū)動器 3-3/4 A/D Converter RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| TC820CLW | 功能描述:LCD 驅(qū)動器 3-3/4 A/D Converter RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| TC820CLW713 | 功能描述:LCD 驅(qū)動器 3-3/4 A/D Converter RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| TC820CPL | 功能描述:LCD 驅(qū)動器 3-3/4 A/D Converter RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
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