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参数资料
| 型号： | ADC08062BIN |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | ADC |
| 英文描述： | 500 ns A/D Converter with S/H Function and Input Multiplexer |
| 中文描述： | 2-CH 8-BIT FLASH METHOD ADC, PARALLEL ACCESS, DIP20 |
| 封装： | DIP-20 |
| 文件页数： | 13/16页 |
| 文件大小： | 307K |
| 代理商： | ADC08062BIN |
Application Information
(Continued)
minimum output voltages above GND can also be compen-
sated by connecting V
to a voltage that is equal to this
minimum voltage. By reducing V
(V
=V
V
)
to less than 5V, the sensitivity of the converter can be in-
creased (i.e., if V
= 2.5V, then 1 LSB = 9.8 mV). The
ADC08061/2’s reference arrangement also facilitates ratio-
metric operation and in many cases the ADC08061/2’s
power supply can be used for transducer power as well as
the V
source. Ratiometric operation is achieved by con-
necting V
to GND and connecting V
and a trans-
ducer’s power supply input to V
+
. The ADC08061/2’s linear-
ity degrades when V
REF+
|V
REF
| is less than 2.0V.
The voltage at V
sets the input level that produces a
digital output of all zeros. Though V
is not itself differential,
the reference design affords nearly differential-input capabil-
ity for some measurement applications. Figure 7 shows one
possible differential configuration.
It should be noted that, while the two V
inputs are fully
differential, the digital output will be zero for any analog input
voltage if V
REF
≥
V
REF+
.
4.0 ANALOG INPUT AND SOURCE IMPEDANCE
The ADC08061/2’s analog input circuitry includes an analog
switch with an “on” resistance of 70
and capacitance of
1.4 pF and 12 pF (see Figure 7). The switch is closed during
the A/D’s input signal acquisition time (while WR is low when
using the WR -RD Mode).Asmall transient current flows into
the input pin each time the switch closes.Atransient voltage,
whose magnitude can increase as the source impedance in-
creases, may be present at the input. So long as the source
impedance is less than 500
, the input voltage transient will
not cause errors and need not be filtered.
Large source impedances can slow the charging of the sam-
pling capacitors and degrade conversion accuracy. There-
fore, only signal sources with output impedances less than
500
should be used if rated accuracy is to be achieved at
the minimum sample time (100 ns maximum). A signal
source with a high output impedance should have its output
buffered with an operational amplifier. Any ringing or voltage
shifts at the op amp’s output during the sampling period can
result in conversion errors.
Correct conversion results will be obtained for input voltages
greater than GND 100 mV and less than V
+
+ 100 mV. Do
not allow the signal source to drive the analog input pin more
than 300 mV higher than V
, or more than 300 mV lower
than GND. The current flowing through any analog input pin
should be limited to 5 mA or less to avoid permanent dam-
age to the IC if an analog input pin is forced beyond these
voltages. The sum of all the overdrive currents into all pins
must be less than 20 mA. Some sort of protection scheme
should be used when the input signal is expected to extend
more than 300 mV beyond the power supply limits. A simple
protection network using resistors and diodes is shown in
Figure 9
6.0 INHERENT SAMPLE-AND-HOLD
An important benefit of the ADC08061/2’s input architecture
is the inherent sample-and-hold (S/H) and its ability to mea-
sure relatively high speed signals without the help of an ex-
ternal S/H. In a non-sampling converter, regardless of its
speed, the input must remain stable to at least
throughout the conversion process if full accuracy is to be
maintained. Consequently, for many high speed signals, this
signal must be externally sampled and held stationary during
the conversion.
The ADC08061 and ADC08062 are suitable for DSP-based
systems because of the direct control of the S/H through the
WR signal. The WR input signal allows the A/D to be syn-
chronized to a DSP system’s sampling rate or to other
ADC08061 and ADC08062s.
1
2
LSB
DS011086-19
*
Represents a multiplexer channel in the ADC08062.
FIGURE 7. ADC08061 and ADC08062 Equivalent Input Circuit Model
www.national.com
13
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相关代理商/技术参数 |
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| ADC08062CIJ | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Single-Ended Data Acquisition System |
| ADC08062CIWM | 制造商:NSC 制造商全称:National Semiconductor 功能描述:500 ns A/D Converter with S/H Function and Input Multiplexer |
| ADC08062CIWM/NOPB | 功能描述:IC ADC 8BIT MPU 2CH MUX 20-SOIC 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:- |
| ADC08062CIWMX | 功能描述:IC CONVERTER A/D 8BIT 20-SOIC 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:- |
| ADC08062CMJ | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Single-Ended Data Acquisition System |
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