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參數(shù)資料
| 型號： | ADC0834 |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | 串行ADC |
| 英文描述： | 8-Bit Serial I/O A/D Converters with Multiplexer Options |
| 中文描述： | 8位串行I /辦公自動化/ D轉換器多路復用選項 |
| 文件頁數(shù)： | 15/26頁 |
| 文件大?。?/td> | 410K |
| 代理商： | ADC0834 |
ML2281, ML2282, ML2284, ML2288
15
ZERO ERROR ADJUSTMENT
The zero of the A/D does not require adjustment. If the
minimum analog input voltage value, V
IN MIN
is not ground,
a zero offset can be done. The converter can be made to
output 00000000 digital code for this minimum input
voltage by biasing any V
IN
– input at this V
IN MIN
value.
This utilizes the differential mode operation of the A/D.
The zero error of the A/D converter relates to the location
of the first riser of the transfer function and can be
measured by grounding the V
IN
– input and applying a
small magnitude positive voltage to the V
IN
+ input. Zero
error is the difference between the actual DC input
voltage which is necessary to just cause an output digital
code transition from 00000000 to 00000001 and the ideal
1/2 LSB value (1/2 LSB = 9.8mV for V
REF
= 5.000V
DC
).
FULL-SCALE ADJUSTMENT
The full-scale adjustment can be made by applying a
differential input voltage which is 1-1/2 LSB down from
the desired analog full-scale voltage range and then
adjusting the magnitude of the V
REF
input or V
CC
for a
digital output code which is just changing from 11111110
to 11111111.
ADJUSTMENT FOR AN ARBITRARY ANALOG
INPUT VOLTAGE RANGE
If the analog zero voltage of the A/D is shifted away from
ground (for example, to accommodate an analog input
signal which does not go to ground), this new zero
reference should be properly adjusted first. A V
IN
+ voltage
which equals this desired zero reference plus 1/2 LSB
CURRENT LIMITING
RESISTOR, I+
≤
15mA
12V
V
CC
V+
GND
I +
→
28.8k
3.2k
3.2k
Figure 8. Shunt Regulator
I+
15mA
V+
5.5V
SLOPE =
6.9V
1
35k
Figure 9. I-V Characteristic of the Shunt Regulator
(where the LSB is calculated for the desired analog span,
1 LSB = analog span/256) is applied to selected “+” input
and the zero reference voltage at the corresponding “–”
input should then be adjusted to just obtain the 00000000
to 00000001 code transition.
The full-scale adjustment should be made by forcing a
voltage to the V
IN
+ input which is given be:
V
fs adjust
V
V
(
V
IN
MAX
MAX
MIN
+
=
×
1 5
.
256
)
where
V
MAX
= high end of the analog input range
V
MIN
= low end (offset zero) of the analog range
The V
REF
or V
CC
voltage is then adjusted to provide a
code change from 11111110 to 11111111.
SHUNT REGULATOR
A unique feature of ML2288 and ML2284 is the inclusion
of a shunt regulator connected from V+ terminal to
ground which also connects to the V
CC
terminal (which is
the actual converter supply) through a silicon diode as
shown in Figure 8. When the regulator is turned on, the
V+ voltage is clamped at 11V
BE
set by the internal resistor
ratio. The typical I-V of the shunt regulator is shown in
Figure 9. It should be noted that before V+ voltage is high
enough to turn on the shunt regulator (which occurs at
about 5.5V), 35k
W
resistance is observed between V+ and
GND. When the shunt regulator is not used, V+ pin
should be either left floating or tied to GND. The
temperature coefficient of the regulator is –22mV/°C.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ADC0834A | 制造商:TI 制造商全稱:Texas Instruments 功能描述:A/D PERIPHERALS WITH SERIAL CONTROL |
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| ADC0834AIN | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Single-Ended Data Acquisition System |
| ADC0834B | 制造商:TI 制造商全稱:Texas Instruments 功能描述:A/D PERIPHERALS WITH SERIAL CONTROL |
| ADC0834BCJ | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:8-Bit Serial I/O A/D Converters with Multiplexer Options |
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