參數資料
型號: AD7859AS
廠商: ANALOG DEVICES INC
元件分類: ADC
英文描述: 3 V to 5 V Single Supply, 200 kSPS 8-Channel, 12-Bit Sampling ADCs
中文描述: 8-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PQFP44
封裝: PLASTIC, QFP-44
文件頁數: 17/28頁
文件大?。?/td> 535K
代理商: AD7859AS
AD7859/AD7859L
REV. A
–17–
REFERENCE SECTION
For specified performance, it is recommended that when using
an external reference, this reference should be between 2.3 V
and the analog supply AV
DD
. The connections for the reference
pins are shown below. If the internal reference is being used,
the REF
IN
/REF
OUT
pin should be decoupled with a 100 nF
capacitor to AGND very close to the REF
IN
/REF
OUT
pin. These
connections are shown in Figure 16.
If the internal reference is required for use external to the ADC,
it should be buffered at the REF
IN
/REF
OUT
pin and a 100 nF
capacitor should be connected from this pin to AGND. The typical
noise performance for the internal reference, with 5V supplies is
150 nV/
Hz
@ 1 kHz and dc noise is 100
μ
V p-p.
AD7859/AD7859L
C
REF1
C
REF2
REF
IN
/REF
OUT
0.1μF
0.01μF
0.1μF
AV
DD
DV
DD
0.1μF
0.1μF
10μF
ANALOG SUPPLY
+3V TO +5V
Figure 16. Relevant Connections Using Internal Reference
The REF
IN
/REF
OUT
pin may be overdriven by connecting it to
an external reference. This is possible due to the series resis-
tance from the REF
IN
/REF
OUT
pin to the internal reference.
This external reference can be in the range 2.3 V to AV
DD
.
When using AV
DD
as the reference source, the 10 nF capacitor
from the REF
IN
/REF
OUT
pin to AGND should be as close as
possible to the REF
IN
/REF
OUT
pin, and also the C
REF1
pin
should be connected to AV
DD
to keep this pin at the same volt-
age as the reference. The connections for this arrangement are
shown in Figure 17. When using AV
DD
it may be necessary to
add a resistor in series with the AV
DD
supply. This has the effect
of filtering the noise associated with the AV
DD
supply.
Note that when using an external reference, the voltage present
at the REF
IN
/REF
OUT
pin is determined by the external refer-
ence source resistance and the series resistance of 150 k
from
the REF
IN
/REF
OUT
pin to the internal 2.5 V reference. Thus, a
low source impedance external reference is recommended.
AD7859/AD7859L
C
REF1
C
REF2
REF
IN
/REF
OUT
0.1μF
0.01μF
0.01μF
AV
DD
DV
DD
0.1μF
0.1μF
10μF
ANALOG SUPPLY
+3V TO +5V
Figure 17. Relevant Connections, AV
DD
as the Reference
AD7859/AD7859L PERFORMANCE CURVES
Figure 18 shows a typical FFT plot for the AD7859 at 200 kHz
sample rate and 10 kHz input frequency.
FREQUENCY – kHz
0
–20
–100
0
100
20
40
60
80
–40
–60
–80
AV
DD
= DV
DD
= 3.3V
F
SAMPLE
= 200kHz
F
IN
= 10kHz
SNR = 72.04dB
THD = –88.43dB
–120
S
Figure 18. FFT Plot
Figure 19 shows the SNR versus Frequency for different sup-
plies and different external references.
INPUT FREQUENCY – kHz
S
74
73
69
0
100
20
40
60
80
72
71
70
AV
DD
= DV
DD
WITH 2.5V REFERENCE
UNLESS STATED OTHERWISE
5.0V SUPPLIES, WITH 5V REFERENCE
5.0V SUPPLIES
5.0V SUPPLIES,
L VERSION
3.3V SUPPLIES
Figure 19. SNR vs. Frequency
Figure 20 shows the Power Supply Rejection Ratio versus Fre-
quency for the part. The Power Supply Rejection Ratio is de-
fined as the ratio of the power in ADC output at frequency f to
the power of a full-scale sine wave.
PSRR (dB) =
10
log (Pf/Pfs)
Pf = Power at frequency f in ADC output, Pfs = power of a full-
scale sine wave. Here a 100 mV peak-to-peak sine wave is
coupled onto the AV
DD
supply while the digital supply is left
unaltered. Both the 3.3 V and 5.0 V supply performances are
shown.
相關PDF資料
PDF描述
AD7859BS 3 V to 5 V Single Supply, 200 kSPS 8-Channel, 12-Bit Sampling ADCs
AD7859L* 5V Low Power RS232 Transceiver; Package: PDIP; No of Pins: 16; Temperature Range: 0°C to +70°C
AD7859LAS 3 V to 5 V Single Supply, 200 kSPS 8-Channel, 12-Bit Sampling ADCs
AD7859L 3 V to 5 V Single Supply, 200 kSPS 8-Channel, 12-Bit Sampling ADCs(單電源,200kSPS 8通道12位采樣A/D轉換器)
AD7859 3 V to 5 V Single Supply, 200 kSPS 8-Channel, 12-Bit Sampling ADCs(單電源,200kSPS 8通道12位采樣A/D轉換器)
相關代理商/技術參數
參數描述
AD7859AS-REEL 制造商:Analog Devices 功能描述:ADC Single SAR 200ksps 12-bit Parallel 44-Pin MQFP T/R 制造商:Rochester Electronics LLC 功能描述:12-BIT 8 CH.SERIAL 200 KSPS I.C. - Tape and Reel
AD7859ASZ 功能描述:IC ADC 12BIT 8CH LP 44-MQFP RoHS:是 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 標準包裝:1 系列:microPOWER™ 位數:8 采樣率(每秒):1M 數據接口:串行,SPI? 轉換器數目:1 功率耗散(最大):- 電壓電源:模擬和數字 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應商設備封裝:24-VQFN 裸露焊盤(4x4) 包裝:Digi-Reel® 輸入數目和類型:8 個單端,單極 產品目錄頁面:892 (CN2011-ZH PDF) 其它名稱:296-25851-6
AD7859ASZ 制造商:Analog Devices 功能描述:IC 12-BIT ADC
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