RSOURCE () T HD ( d B) –40 –45 –" />
參數(shù)資料
型號： AD7938BSUZ-REEL7
廠商： Analog Devices Inc
文件頁數(shù)： 13/36頁
文件大?。?/td> 0K
描述： IC ADC 12BIT 8CHAN 32TQFP
標準包裝： 500
位數(shù)： 12
采樣率（每秒）： 1.5M
數(shù)據(jù)接口： 并聯(lián)
轉(zhuǎn)換器數(shù)目： 1
功率耗散（最大）： 13.5mW
電壓電源： 單電源
工作溫度： -40°C ~ 85°C
安裝類型： 表面貼裝
封裝/外殼： 32-TQFP
供應(yīng)商設(shè)備封裝： 32-TQFP（7x7）
包裝： 帶卷 (TR)
輸入數(shù)目和類型： 8 個單端，單極；4 個差分，單極；4 個偽差分，單極；7 偽差分，單極
配用： EVAL-AD7938CBZ-ND - EVAL BOARD FOR AD7938
AD7938/AD7939
Data Sheet
Rev. C | Page 20 of 36
RSOURCE ()
T
HD
(
d
B)
–40
–45
–50
–55
–80
–75
–70
–65
–60
–90
–85
10
100
1k
03715-
018
FIN = 50kHz
VDD = 5V
VDD = 3V
Figure 21. THD vs. Source Impedance in Single-Ended Mode
RSOURCE ()
T
HD
(
d
B)
–60
–80
–75
–70
–65
–100
–85
–90
–95
10
100
1k
03715-
019
FIN = 50kHz
VDD = 5V
VDD = 3V
Figure 22. THD vs. Source Impedance in Fully Differential Mode
Figure 23 shows a graph of the THD vs. the analog input
frequency for various supplies while sampling at 1.5 MHz
with an SCLK of 25.5 MHz. In this case, the source impedance
is 10 .
INPUT FREQUENCY (kHz)
T
HD
(
d
B)
–50
–60
–70
–80
–110
–100
–90
–120
0
100
400
200
300
600
500
700
03715-
020
FSAMPLE = 1.5MSPS
RANGE = 0 TO VREF
VDD = 3V
SINGLE-ENDED MODE
VDD = 5V/3V
DIFFERENTIAL MODE
VDD = 5V
SINGLE-ENDED MODE
Figure 23. THD vs. Analog Input Frequency for Various Supply Voltages
ANALOG INPUTS
The AD7938/AD7939 have software-selectable analog input
configurations. The user can choose eight single-ended inputs,
four fully differential pairs, four pseudo differential pairs, or
seven pseudo differential inputs. The analog input
configuration is chosen by setting the MODE0/MODE1 bits in
the internal control register (see Table 10).
Single-Ended Mode
The AD7938/AD7939 can have eight single-ended analog input
channels by setting the MODE0 and MODE1 bits in the control
register to 0. In applications where the signal source has a high
impedance, it is recommended to buffer the analog input before
applying it to the ADC. An op amp suitable for this function is
the AD8021. The analog input range of the AD7938/AD7939
can be programmed to be either 0 V to VREF or 0 V to 2 × VREF.
If the analog input signal to be sampled is bipolar, the internal
reference of the ADC can be used to externally bias up this
signal to make it the correct format for the ADC.
Figure 24 shows a typical connection diagram when operating
the ADC in single-ended mode. This diagram shows a bipolar
signal of amplitude ±1.25 V being preconditioned before it is
applied to the AD7938/AD7939. In cases where the analog
input amplitude is ±2.5 V, the 3R resistor can be replaced with a
resistor of value R. The resultant voltage on the analog input of
the AD7938/AD7939 is a signal ranging from 0 V to 5 V. In this
case, the 2 × VREF mode can be used.
0.47F
+1.25V
VIN
R
3R
0V
–1.25V
+2.5V
0V
VIN0
VIN7
VREFOUT
AD7938/
AD7939*
R
*ADDITIONAL PINS OMITTED FOR CLARITY.
03715-
031
Figure 24. Single-Ended Mode Connection Diagram
Differential Mode
The AD7938/AD7939 can have four differential analog input
pairs by setting the MODE0 and MODE1 bits in the control
register to 0 and 1, respectively.
Differential signals have some benefits over single-ended
signals, including noise immunity based on the device’s
common-mode rejection and improvements in distortion
performance. Figure 25 defines the fully differential analog
input of the AD7938/AD7939.
相關(guān)PDF資料
PDF描述
13280-18PG-331 CONN PLUG 18POS CABLE PIN
E5MSCB CONN RCPT 5POS MALE SLD CUP BLK
E5MRAB CONN RCPT 5POS MALE R/A PCB BLK
AD7898AR-3 IC ADC 12BIT SRL HS 5V 8-SOIC
MS3106F24-12S CONN PLUG 5POS STRAIGHT W/SCKT
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD7939 制造商:AD 制造商全稱:Analog Devices 功能描述:8-Channel, 1.5 MSPS, 12-Bit and 10-Bit Parallel ADCs with a Sequencer
AD7939BCP 制造商:Analog Devices 功能描述:ADC Single SAR 1.5Msps 10-bit Parallel 32-Pin LFCSP EP
AD7939BCP-REEL 制造商:Analog Devices 功能描述:ADC SGL SAR 1.5MSPS 10-BIT PARALLEL 32LFCSP EP - Tape and Reel
AD7939BCP-REEL7 制造商:Analog Devices 功能描述:ADC Single SAR 1.5Msps 10-bit Parallel 32-Pin LFCSP EP T/R 制造商:Analog Devices 功能描述:ADC SGL SAR 1.5MSPS 10-BIT PARALLEL 32LFCSP EP - Tape and Reel
AD7939BCPZ 功能描述:IC ADC 10BIT 8CH PARALL 32LFCSP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標準包裝:1,000 系列:- 位數(shù):16 采樣率（每秒）:45k 數(shù)據(jù)接口:串行 轉(zhuǎn)換器數(shù)目:2 功率耗散（最大）:315mW 電壓電源:模擬和數(shù)字 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:28-SOIC W 包裝:帶卷 (TR) 輸入數(shù)目和類型:2 個單端，單極
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*