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參數(shù)資料
| 型號(hào)： | AME811CPL |
| 廠商： | AME, Inc. |
| 元件分類： | 顯示驅(qū)動(dòng)器 |
| 英文描述： | 3-1/2 Digit A/D Converter - Low Power With HOLD And Differential Reference Inputs |
| 中文描述： | 3-1/2位A / D轉(zhuǎn)換-低的持有和差分基準(zhǔn)輸入功率 |
| 文件頁(yè)數(shù)： | 11/15頁(yè) |
| 文件大小： | 905K |
| 代理商： | AME811CPL |
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Analog Microelectronics, Inc.
11
AME811/AME811A/AME811R
3-1/2 Digit A/D Converter - Low Power
With HOLD And Differential Reference Inputs
Integrating Capacitor (Cint)
Cint should be selected to maximize the integrator out-
put voltage swing without causing output saturation. A
±
2V full-scale integrator output swing is recommended
if “ANALOG COMMON” is used as signal reference.
For 3 readings/second (fosc = 48 KHz) a 0.22
μ
F value
is suggested. If a different oscillator frequency is used,
Cint must be changed in inverse proportion to maintain
the nominal
±
2V integrator swing. An exact expres-
sion for Cint is:
Cint = [(4000)(1/fosc)(Vfs/Rint)] / Vint
where:
fosc= Oscillator clock frequency
Vfs = Full-scale input voltage
Rint = Integrating resistor
Vint = Desired full-scale integrator output swing
Cint must have low dielectric absorption to minimize
rollover error. A polypropylene capacitor is recom-
mended.
Integrating Resistor (Rint)
The input buffer amplifier and integrator both have a
class A output stage with 100
μ
A quiescent current.
The integrator and buffer can supply 20
μ
A drive cur-
rents with negligible linearity errors. Rint is chosen to
keep the output stage in the linear region. For a 200mV
full-scale, it is 47K
; 2.0V full-scale requires 470K
.
Summary of component selection:
Note: fosc = 48 KHz
Oscillator Components
R-C Oscillator
A 100 K
Rosc is recommended for all frequencies.
Cosc is selected by using the equation:
fosc = 0.45/(RC)
For fosc of 48KHz, Cosc is 100pF nominally.
To achieve maximum line noise rejection, the signal-
integrate period should be a multiple of line period. The
optimum oscillator frequencies for 60 Hz and 50 Hz
rejection are listed as follows:
For 60 Hz rejection:
40KHz, 48KHz, 60KHz etc.
For 50 Hz rejection:
40KHz, 50KHz, 66-2/3KHz etc.
Reference Voltage Selection
A full-scale reading (2000 counts) requires the input
signal be twice the reference voltage.
In some applications a scale factor other than unity may
exist between a transducer output voltage and the re-
quired digital reading. Assume, for example, a pres-
sure transducer output is 600 mV for 2000 Ib/in
2
. Rather
than dividing the input voltage by three the reference
voltage should be set to 300 mV. This permits the trans-
ducer input to be used directly. The integrator resistor
would be 120K
. In some temperature and weighting
system with variable tare, the offset reading can be
generated by connecting the voltage transducer be-
tween INHI and COMMON and the variable offset volt-
age between COMMON and INLO.
Low Battery Flag (LB)
The low battery flag is set when the supply voltage (V+
to V-) is lower than seven volts, typical. Once the LB is
set, the waveform of the LB will be out of phase with
the BP (Back Plane) to turn on a low battery annuncia-
tor for AME811.
F u ll sc a le
C a z
R in t
C in t
V re f
2 0 0 .0 m V
0 .4 7
μ
F
4 7 K
0 .2 2
μ
F
1 0 0 .0 m V
2 .0 0 0 V
0 .0 4 7
μ
F
4 7 0 K
0 .2 2
μ
F
1 .0 0 0 V
Full-S ca le V olta ge
200.0 m V
2.000 V
V re f
100.0 m V
1.000 V
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相關(guān)代理商/技術(shù)參數(shù) |
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| AME811R | 制造商:AME 制造商全稱:Analog Microelectronics 功能描述:3-1/2 Digit A/D Converter - Low Power With HOLD And Differential Reference Inputs |
| AME811RCPL | 制造商:AME 制造商全稱:Analog Microelectronics 功能描述:3-1/2 Digit A/D Converter - Low Power With HOLD And Differential Reference Inputs |
| AME8500 | 制造商:AME 制造商全稱:Analog Microelectronics 功能描述:Micropower uP Reset Family |
| AME8500AEET | 制造商:AME 制造商全稱:Analog Microelectronics 功能描述:Micropower uP Reset Family |
| AME8500AEETAA15 | 制造商:AME 制造商全稱:Analog Microelectronics 功能描述:UProcessor Supervisory |
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