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參數(shù)資料
| 型號： | SP8531 |
| 元件分類： | ADC |
| 英文描述： | 12-Bit Sampling Serial Out Analog to Digital Converter |
| 中文描述： | 12位抽樣模擬數(shù)字轉換器系列 |
| 文件頁數(shù)： | 6/16頁 |
| 文件大?。?/td> | 256K |
| 代理商： | SP8531 |
SP8531DS/01 SP8531 12-Bit Sampling Serial Out Analog to Digital Converter
Copyright 1999 Sipex Corporation
6
Figure 1. Operating Circuit
Input Impedance
The input of the
SP8531
can be modeled as a
resistor in series with a ground referenced DC
voltage source of 1.0 volt. Note that the input
resistor is a switched capacitor resistor and so its
value is inversely proportional to conversion
rate. When the ADC is in free running mode
with a 4 MHz clock applied (a conversion rate of
235 Ksps) the input resistance is nominally
600K. At a conversion rate of 117.5 Ksps the
input resistor value would double to 1.2
megohms. In order to avoid introducing an un-
adjusted gain error greater than 1 lsb, the device
must be driven by a source whose resistance is
4096 times smaller than its input impedance. At
the 4 MHz clock rate this would require a source
whose resistance was less than 146 Ohms.
Layout Considerations
Because of the high resolution and linearity of
the
SP8531
, system design considerations such
as ground path impedance and contact
resistance become very important.
1
16
GAIN ADJ UST
N.C.
2
15
REF OUT
N.C.
3
14
V
IN
4
13
OFFSET ADJ .
AGND
5
12
V
DA
V
SS
6
11
V
DD
SCLK
7
10
SD
D
OUT
8
9
CS
STATUS
SP8531
V
IN
SHUTDOWN
CHIP SELECT
STATUS OUT
DATA OUT
CLOCK IN
10kOhms
*Optional filter capacitor is helpful in a noisy pc board application.
2kOhms
5kOhms
N.C.
+5V
0.1
μ
F
0.1
μ
F
6.8
μ
F
+
6.8
μ
F
To avoid introducing distortion when driving
the analog inputs of these devices, the source
resistance must be very low, or constant with
signal level. Note that in the operating circuit
there is no connection made between VDA
(Pin 12) and the system power supply. This is
because the analog supply pin (VDA) is
connected internally to the digital supply pin
(VDD) through a ten ohm resistor.
This ten ohm resistor when combined with a
parallel combination of 6.8
μ
F tantalum and
0.1
μ
F ceramic capacitor between VDA and
analog ground, will provide some immunity to
noise which resides on the system supply. To
maintain maximum system accuracy, the
supply connected to the VDD pin should be well
isolated from digital supplies and wide load
variations.
To limit effects of digital switching elsewhere
in a system, it often makes sense to run a
separate +5V supply conductor from the supply
相關PDF資料 |
PDF描述 |
|---|---|
| SP8531AN | 12-Bit Sampling Serial Out Analog to Digital Converter |
| SP8531AS | 12-Bit Sampling Serial Out Analog to Digital Converter |
| SP8531BN | 12-Bit Sampling Serial Out Analog to Digital Converter |
| SP8531BS | 12-Bit Sampling Serial Out Analog to Digital Converter |
| SP8531JN | 12-Bit Sampling Serial Out Analog to Digital Converter |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| SP8531AN | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:12-Bit Sampling Serial Out Analog to Digital Converter |
| SP8531AS | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:12-Bit Sampling Serial Out Analog to Digital Converter |
| SP8531BN | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:12-Bit Sampling Serial Out Analog to Digital Converter |
| SP8531BS | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:12-Bit Sampling Serial Out Analog to Digital Converter |
| SP8531JN | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:12-Bit Sampling Serial Out Analog to Digital Converter |
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