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參數(shù)資料
| 型號： | ADC12048CIVF |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | ADC |
| 英文描述： | 12-Bit Plus Sign 216 kHz 8-Channel Sampling Analog-to-Digital Converter |
| 中文描述： | 1-CH 13-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQFP44 |
| 封裝： | PLASTIC, QFP-44 |
| 文件頁數(shù)： | 27/30頁 |
| 文件大小： | 635K |
| 代理商： | ADC12048CIVF |
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Analog Application Information
(Continued)
pacitors should be placed as close as physically possible to
the supply and ground pins with the smaller capacitor closer
to the device. The capacitors also should have the shortest
possible leads in order to minimize series lead inductance.
Surface mount chip capacitors are optimal in this respect
and should be used when possible.
When the power supply regulator is not local on the board,
adequate bypassing (a high value electrolytic capacitor)
should be placed at the power entry point. The value of the
capacitor depends on the total supply current of the circuits
on the PC board. All supply currents should be supplied by
the capacitor instead of being drawn from the external sup-
ply lines, while the external supply charges the capacitor at a
steady rate.
The ADC has two V
+ and DGND pins. It is recommended
that each of these V
+ pins be separately bypassed to
DGND with a 0.1 μF plus a 10 μF capacitor. The layout dia-
gram of Figure 21 shows the recommended placement for
the supply bypass capacitors.
PC BOARD LAYOUT AND GROUNDING
CONSIDERATlONS
To get the best possible performance from the ADC12048,
the printed circuit boards should have separate analog and
digital ground planes. The reason for using two ground
planes is to prevent digital and analog ground currents from
sharing the same path until they reach a very low impedance
power supply point. This will prevent noisy digital switching
currents from being injected into the analog ground.
Figure 21 illustrates a favorable layout for ground planes,
power supply and reference input bypass capacitors. It
shows
a
layout
using
a
through-hole assembly. A similar approach should be used
for the PQFP package.
44-pin
PLCC
socket
and
The analog ground plane should encompass the area under
the analog pins and any other analog components such as
the reference circuit, input amplifiers, signal conditioning cir-
cuits, and analog signal traces.
The digital ground plane should encompass the area under
the digital circuits and the digital input/output pins of the
ADC12048. Having a continuous digital ground plane under
the data and clock traces is very important. This reduces the
overshoot/undershoot and high frequency ringing on these
lines that can be capacitively coupled to analog circuitry sec-
tions through stray capacitances.
The AGND and DGND in the ADC12048 are not internally
connected together. They should be connected together on
the PC board right at the chip. This will provide the shortest
return path for the signals being exchanged between the in-
ternal analog and digital sections of the ADC.
It is also a good design practice to have power plane layers
in the PC board. This will improve the supply bypassing (an
effective distributed capacitance between power and ground
plane layers) and voltage drops on the supply lines. How-
ever, power planes are not as essential as ground planes are
for satisfactory performance. If power planes are used, they
should be separated into two planes and the area and con-
nections should follow the same guidelines as mentioned for
the ground planes. Each power plane should be laid out over
its associated ground planes, avoiding any overlap between
power and ground planes of different types. When the power
planes are not used, it is recommended to use separate sup-
ply traces for the V
A
+ and V
D
+ pins from a low impedance
supply point (the regulator output or the power entry point to
the PC board). This will help ensure that the noisy digital
supply does not corrupt the analog supply.
A
www.national.com
27
相關PDF資料 |
PDF描述 |
|---|---|
| ADC12048 | 12-Bit Plus Sign 216 kHz 8-Channel Sampling Analog-to-Digital Converter |
| ADC12048CIV | 12-Bit Plus Sign 216 kHz 8-Channel Sampling Analog-to-Digital Converter |
| ADC1205CCJ-1 | 12-Bit Plus Sign mP Compatible A/D Converters |
| ADC1225 | 12-Bit Plus Sign mP Compatible A/D Converters |
| ADC1205 | 12-Bit Plus Sign mP Compatible A/D Converters |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ADC12048CIVF/NOPB | 功能描述:模數(shù)轉換器 - ADC 12B PLUS SIGN 216KHz 8CH SAMPLING ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結構:Sigma-Delta 轉換速率: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 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADC12048CIVF/NOPB | 制造商:Texas Instruments 功能描述:A/D Converter (A-D) IC |
| ADC12048EVAL | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:12-Bit Plus Sign 216 kHz 8-Channel Sampling Analog-to-Digital Converter |
| ADC1205 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:12-Bit Plus Sign mP Compatible A/D Converters |
| ADC1205BCJ | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog-to-Digital Converter， 13-Bit |
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