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參數資料
| 型號： | AD7854BR |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | ADC |
| 英文描述： | 3 V to 5 V Single Supply, 200 kSPS 12-Bit Sampling ADCs |
| 中文描述： | 1-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PDSO28 |
| 封裝： | SOIC-28 |
| 文件頁數： | 15/28頁 |
| 文件大小： | 264K |
| 代理商： | AD7854BR |
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AD7854/AD7854L
REV. B
–
15
–
Transfer Functions
For the unipolar range the designed code transitions occur
midway between successive integer LSB values (i.e., 1/2 LSB,
3/2 LSBs, 5/2 LSBs . . . FS
–
3/2 LSBs). The output coding is
straight binary for the unipolar range with 1
LSB = FS
/4096
=
3.3
V/
4096
=
0.8
mV
when
V
REF
= 3.3
V
. The ideal input/
output transfer characteristic for the unipolar range is shown in
Figure 14.
OUTPUT
CODE
111...111
111...110
111...101
111...100
000...011
000...010
000...001
000...000
0V 1LSB
V
IN
= (AIN(+)
–
AIN(
–
)), INPUT VOLTAGE
+FS
–
1LSB
1LSB =4096
Figure 14. AD7854/AD7854L Unipolar Transfer
Characteristic
Figure 13 shows the AD7854/AD7854L
’
s
±
V
REF
/2 bipolar ana-
log input configuration. AIN(+) cannot go below 0 V, so for the
full bipolar range, AIN(
–
) should be biased to at least +V
REF
/2.
Once again the designed code transitions occur midway between
successive integer LSB values. The output coding is twos
complement with 1
LSB =
4096
=
3.3
V
/4096
=
0.8
mV
. The
ideal input/output transfer characteristic is shown in Figure 15.
OUTPUT
CODE
011...111
011...110
000...001
111...111
000...000
000...010
000...001
000...000
V
IN
= (AIN(+)
–
AIN(
–
)), INPUT VOLTAGE
1LSB =4096
0V
(V
REF
/2)
–
1LSB
(V
REF
/2) + 1 LSB
V
REF
/2
+ FS
–
1LSB
FS = V
REF
V
Figure 15. AD7854/AD7854L Bipolar Transfer Characteristic
Input Ranges
The analog input range for the AD7854/AD7854L is 0 V to
V
REF
in both the unipolar and bipolar ranges.
The only difference between the unipolar range and the bipolar
range is that in the bipolar range the AIN(
–
) should be biased
up to at least +V
REF
/2 and the output coding is twos comple-
ment (see Table V and Figures 14 and 15).
Table V. Analog Input Connections
Analog Input
Range
0 V to V
REF1
±
V
REF
/2
2
Input Connections
AIN(+)
Connection
Diagram
AIN(–)
V
IN
V
IN
AGND
V
REF
/2
Figure 12
Figure 13
NOTES
1
Output code format is straight binary.
2
Range is
±
V
REF
/2 biased about V
REF
/2. Output code format is twos complement.
Note that the AIN(
–
) pin on the AD7854/AD7854L can be
biased up above AGND in the unipolar mode, or above V
REF
/2
in bipolar mode if required. The advantage of biasing the lower
end of the analog input range away from AGND is that the analog
input does not have to swing all the way down to AGND. Thus,
in single supply applications the input amplifier does not have to
swing all the way down to AGND. The upper end of the analog
input range is shifted up by the same amount. Care must be
taken so that the bias applied does not shift the upper end of the
analog input above the AV
DD
supply. In the case where the ref-
erence is the supply, AV
DD
, the AIN(
–
) should be tied to AGND
in unipolar mode or to AV
DD
/2 in bipolar mode.
. . .
AIN(+)
AIN(
–
)
V
IN
= 0 TO V
REF
TRACK AND HOLD
AMPLIFIER
DB0
DB11
STRAIGHT
BINARY
FORMAT
AD7854/AD7854L
Figure 12. 0 to V
REF
Unipolar Input Configuration
2
’
S
COMPLEMENT
FORMAT
V
REF
/2
. . .
AIN(+)
AIN(
–
)
V
IN
= 0 TO V
REF
TRACK AND HOLD
AMPLIFIER
DB0
DB11
AD7854/AD7854L
Figure 13.
±
V
REF
/2 about V
REF
/2 Bipolar Input Configuration
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相關代理商/技術參數 |
參數描述 |
|---|---|
| AD7854BR-REEL | 制造商:Analog Devices 功能描述:ADC Single SAR 200ksps 12-bit Parallel 28-Pin SOIC W T/R |
| AD7854BRZ | 功能描述:IC ADC 12BIT PARALLEL LP 28-SOIC RoHS:是 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 位數:12 采樣率（每秒）:3M 數據接口:- 轉換器數目:- 功率耗散（最大）:- 電壓電源:- 工作溫度:- 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應商設備封裝:SOT-23-6 包裝:帶卷 (TR) 輸入數目和類型:- |
| AD7854L | 制造商:AD 制造商全稱:Analog Devices 功能描述:3 V to 5 V Single Supply, 200 kSPS 12-Bit Sampling ADCs |
| AD7854LAQ | 制造商:Rochester Electronics LLC 功能描述:12 BIT SINGLE CHANNEL PARALLEL ADC I.C. - Bulk |
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