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參數(shù)資料
| 型號(hào)： | ICL7137 |
| 廠商： | Intersil Corporation |
| 元件分類： | 串行ADC |
| 英文描述： | 3 1/2 Digit LED, Low Power Display,A/D Converters(3 1/2 位用于低功耗LED的A/D轉(zhuǎn)換器) |
| 中文描述： | 低功耗、3 1/2位A/D轉(zhuǎn)換器 |
| 文件頁數(shù)： | 7/15頁 |
| 文件大?。?/td> | 497K |
| 代理商： | ICL7137 |
7
FN3086.6
July 21, 2005
are connected to the external pins. The converter then
integrates the differential voltage between IN HI and IN LO
for a fixed time. This differential voltage can be within a wide
common mode range: up to 1V from either supply. If, on the
other hand, the input signal has no return with respect to the
converter power supply, IN LO can be tied to analog
COMMON to establish the correct common mode voltage. At
the end of this phase, the polarity of the integrated signal is
determined.
De-Integrate Phase
The final phase is de-integrate, or reference integrate. Input
low is internally connected to analog COMMON and input
high is connected across the previously charged reference
capacitor. Circuitry within the chip ensures that the capacitor
will be connected with the correct polarity to cause the
integrator output to return to zero. The time required for the
output to return to zero is proportional to the input signal.
Specifically the digital reading displayed is:
.
Zero Integrator Phase
The final phase is zero integrator. First, input low is shorted to
analog COMMON. Second, the reference capacitor is charged
to the reference voltage. Finally, a feedback loop is closed
around the system to IN HI to cause the integrator output to
return to zero. Under normal conditions, this phase lasts for
between 11 to 140 clock pulses, but after a “heavy” overrange
conversion, it is extended to 740 clock pulses.
Differential Input
The input can accept differential voltages anywhere within the
common mode range of the input amplifier, or specifically from
0.5V below the positive supply to 1V above the negative supply.
In this range, the system has a CMRR of 86dB typical.
However, care must be exercised to assure the integrator
output does not saturate. A worst case condition would be a
large positive common mode voltage with a near full scale
negative differential input voltage. The negative input signal
drives the integrator positive when most of its swing has been
used up by the positive common mode voltage. For these
critical applications the integrator output swing can be reduced
to less than the recommended 2V full scale swing with little loss
of accuracy. The integrator output can swing to within 0.3V of
either supply without loss of linearity.
Differential Reference
The reference voltage can be generated anywhere within the
power supply voltage of the converter. The main source of
common mode error is a roll-over voltage caused by the
reference capacitor losing or gaining charge to stray
capacity on its nodes. If there is a large common mode
voltage, the reference capacitor can gain charge (increase
voltage) when called up to de-integrate a positive signal but
lose charge (decrease voltage) when called up to de-
integrate a negative input signal. This difference in reference
for positive or negative input voltage will give a roll-over
error. However, by selecting the reference capacitor such
that it is large enough in comparison to the stray
capacitance, this error can be held to less than 0.5 count
worst case. (See Component Value Selection.)
DISPLAY READING = 1000
V
REF
--------------
DE-
DE+
C
INT
C
AZ
R
INT
BUFFER
A-Z
INT
-
+
A-Z
COMPARATOR
IN HI
COMMON
IN LO
31
32
30
DE-
DE+
INT
A-Z
34
C
REF+
36
REF HI
C
REF
REF LO
35
A-Z,
ZI
A-Z,
33
C
REF
-
28
29
27
TO
DIGITAL
SECTION
A-Z AND DE
(±)
AND ZI
INTEGRATOR
INT
STRAY
STRAY
V+
10
μ
A
V-
N
INPUT
HIGH
2.8V
6.2V
V+
1
INPUT
LOW
-
+
-
+
-
+
ZI
ZI
26
FIGURE 2. ANALOG SECTION OF ICL7136
ICL7136
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ICL7137C/D | 功能描述:顯示驅(qū)動(dòng)器和控制器 RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel |
| ICL7137CDL | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ICL7137CJL | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ICL7137CM44 | 制造商:Rochester Electronics LLC 功能描述:44 PQFP, 0 + 70, 3 1/2 DIG A/D (LED DRIVE) - Bulk |
| ICL7137CMH | 制造商:Maxim Integrated Products 功能描述:LOW POWER, 3 1/2 DIGIT ADC WITH DIRECT LED DR - Rail/Tube 制造商:Rochester Electronics LLC 功能描述: |
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