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参数资料
| 型号： | ADC0805LCN |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | ADC |
| 英文描述： | 8-Bit uP Compatible A/D Converters |
| 中文描述： | 1-CH 8-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PDIP20 |
| 封装： | PLASTIC, DIP-20 |
| 文件页数： | 22/41页 |
| 文件大小： | 1118K |
| 代理商： | ADC0805LCN |
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Functional Description
(Continued)
2.5 Errors and Reference Voltage Adjustments
2.5.1 Zero Error
The zero of the A/D does not require adjustment. If the mini-
mum analog input voltage value, V
, is not ground, a
zero offset can be done. The converter can be made to out-
put 0000 0000 digital code for this minimum input voltage by
biasing the A/D V
() input at this V
value (see Appli-
cations section). 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
() input and applying a small magnitude
positive voltage to the V
(+) input. Zero error is the differ-
ence between the actual DC input voltage that is necessary
to just cause an output digital code transition from 0000 0000
to 0000 0001 and the ideal
1
2
LSB value (
1
2
LSB = 9.8 mV
for V
REF
/2=2.500 V
DC
).
2.5.2 Full-Scale
The full-scale adjustment can be made by applying a differ-
ential input voltage that is 1
1
2
LSB less than the desired ana-
log full-scale voltage range and then adjusting the magni-
tude of the V
/2 input (pin 9 or the V
supply if pin 9 is
not used) for a digital output code that is just changing from
1111 1110 to 1111 1111.
2.5.3 Adjusting 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
that does not go to ground) this new zero reference should
be properly adjusted first. A V
(+) voltage that equals this
desired zero reference plus
1
2
LSB (where the LSB is calcu-
lated for the desired analog span, 1 LSB=analog span/256)
is applied to pin 6 and the zero reference voltage at pin 7
should then be adjusted to just obtain the 00
HEX
to 01
HEX
code transition.
The full-scale adjustment should then be made (with the
proper V
() voltage applied) by forcing a voltage to the
V
IN
(+) input which is given by:
where:
V
MAX
=The high end of the analog input range
and
V
=the low end (the offset zero) of the analog range.
(Both are ground referenced.)
The V
/2 (or V
) voltage is then adjusted to provide a
code change from FE
HEX
to FF
HEX
. This completes the ad-
justment procedure.
2.6 Clocking Option
The clock for the A/D can be derived from the CPU clock or
an external RC can be added to provide self-clocking. The
CLK IN (pin 4) makes use of a Schmitt trigger as shown in
Figure 8
DS005671-87
a) Analog Input Signal Example
DS005671-88
*
Add if V
REF
/2
≤
1 V
DC
with LM358 to draw 3 mA to ground.
b) Accommodating an Analog Input from
0.5V (Digital Out = 00
HEX
) to 3.5V
(Digital Out=FF
HEX
)
FIGURE 7. Adapting the A/D Analog Input Voltages to Match an Arbitrary Input Signal Range
A
www.national.com
22
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相关代理商/技术参数 |
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|---|---|
| ADC0805LCN/A+ | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Analog-to-Digital Converter， 8-Bit |
| ADC0805LCN/B+ | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Analog-to-Digital Converter， 8-Bit |
| ADC0805LCN/NOPB | 功能描述:IC ADC 8BIT MPU COMPAT 20-DIP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 位数:12 采样率（每秒）:3M 数据接口:- 转换器数目:- 功率耗散（最大）:- 电压电源:- 工作温度:- 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-23-6 包装:带卷 (TR) 输入数目和类型:- |
| ADC0806 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:8-Bit, 20 MSPS to 60 MSPS, 1.3 mW/MSPS A/D Converter |
| ADC08060 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:8-Bit, 20 MSPS to 60 MSPS, 1.3 mW/MSPS A/D Converter |
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