- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄2139 > ADA4940-1ARZ-R7 (Analog Devices Inc)IC DIFF ADC DVR 18BIT LN 8SOIC PDF資料下載
參數(shù)資料
| 型號： | ADA4940-1ARZ-R7 |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 19/33頁 |
| 文件大小： | 0K |
| 描述： | IC DIFF ADC DVR 18BIT LN 8SOIC |
| 標(biāo)準(zhǔn)包裝： | 1,000 |
| 放大器類型： | 差分 |
| 電路數(shù)： | 1 |
| 輸出類型： | 差分 |
| 轉(zhuǎn)換速率： | 95 V/µs |
| -3db帶寬： | 260MHz |
| 電流 - 輸入偏壓： | 1.1µA |
| 電壓 - 輸入偏移： | 60µV |
| 電流 - 電源： | 1.25mA |
| 電流 - 輸出 / 通道： | 46mA |
| 電壓 - 電源，單路/雙路(±)： | 3 V ~ 6 V |
| 工作溫度： | -40°C ~ 125°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 8-SOIC（0.154"，3.90mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 8-SO |
| 包裝： | 帶卷 (TR) |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁當(dāng)前第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁第33頁
Data Sheet
ADA4940-1/ADA4940-2
Rev. C | Page 25 of 32
Terminating a Single-Ended Input
This section describes how to properly terminate a single-ended
and RG = 1 k. An example using an input source with a terminated
output voltage of 1 V p-p and source resistance of 50 illustrates
the three steps that must be followed. Because the terminated
output voltage of the source is 1 V p-p, the open-circuit output
voltage of the source is 2 V p-p. The source shown in Figure 66
indicates this open-circuit voltage.
RS
50
VS
2V p-p
RIN, se
1.33k
ADA4940-1
ADA4940-2
RL VOUT, dm
+VS
–VS
RG
1k
RG
1k
RF
1k
RF
1k
VOCM
08452-
059
Figure 66. Calculating Single-Ended Input Impedance, RIN
1. The input impedance is calculated by
Ω
k
.33
1
)
1000
(
2
1000
1
1000
)
(
2
1
,
=
+
×
=
+
×
=
F
G
F
G
se
IN
R
2. To match the 50 source resistance, calculate the
termination resistor, RT, using RT||1.33 k = 50 .
The closest standard 1% value for RT is 52.3 .
ADA4940-1
ADA4940-2
RL
VOUT, dm
+VS
–VS
RS
50
RG
1k
RG
1k
RF
1k
RF
1k
VOCM
VS
2V p-p
RIN, se
50
RT
52.3
08452-
060
Figure 67. Adding Termination Resistor RT
loop is now greater than the RG in the lower loop due to the
addition of the termination resistors. To compensate for the
imbalance of the gain resistors, add a correction resistor (RTS)
in series with RG in the lower loop. RTS is the Thevenin
equivalent of the source resistance, RS, and the termination
resistance, RT, and is equal to RS||RT.
RS
50
VS
2V p-p
RT
52.3
RTH
25.5
VTH
1.02V p-p
08452-
061
Figure 68. Calculating the Thevenin Equivalent
RTS = RTH = RS||RT = 25.5 . Note that VTH is greater than
1 V p-p, which was obtained with RT = 50 . The modified
circuit with the Thevenin equivalent (closest 1% value used for
RTH) of the terminated source and RTS in the lower feedback
loop is shown in Figure 69.
ADA4940-1
ADA4940-2
RL VOUT, dm
+VS
–VS
RTH
25.5
RG
1k
RG
1k
RF
1k
RF
1k
VOCM
VTH
1.02V p-p
RTS
25.5
08452-
062
Figure 69. Thevenin Equivalent and Matched Gain Resistors
Figure 69 presents a tractable circuit with matched feedback
loops that can be easily evaluated.
It is useful to point out two effects that occur with a terminated
input. The first is that the value of RG is increased in both loops,
lowering the overall closed-loop gain. The second is that VTH
is a little larger than 1 V p-p, as it would be if RT = 50 .
These two effects have opposite impacts on the output voltage,
and for large resistor values in the feedback loops (~1 k), the
effects essentially cancel each other out. For small RF and RG,
or high gains, however, the diminished closed-loop gain is not
cancelled completely by the increased VTH. This can be seen by
evaluating Figure 69.
The desired differential output in this example is 1 V p-p
because the terminated input signal was 1 V p-p and the
closed-loop gain = 1. The actual differential output voltage,
however, is equal to (1.02 V p-p)(1000/1025.5) = 0.996 V p-p.
This is within the tolerance of the resistors, so no change to
the feedback resistor, RF, is required.
INPUT COMMON-MODE VOLTAGE RANGE
The ADA4940-1/ADA4940-2 input common-mode range is
shifted down by approximately 1 VBE, in contrast to other ADC
drivers with centered input ranges, such as the ADA4939-1/
ADA4939-2. The downward-shifted input common-mode range
is especially suited to dc-coupled, single-ended-to-differential,
and single-supply applications.
For ±2.5 V or +5 V supply operation, the input common-mode
range at the summing nodes of the amplifier is specified as 2.7 V
to +1.3 V or 0.2 V to 3.8 V, and is specified as 0.2 V to +1.8 V
with a +3 V supply.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ADA4950-1YCPZ-RL | IC AMP DIFF LP 114MA 16LFCSP |
| ADEL2020ARZ-20-RL | IC OPAMP CF LN LP 60MA 20SOIC |
| ADL5561ACPZ-R7 | IC AMP DIFF RF/IF 2.9GHZ 16LFCSP |
| ADL5562ACPZ-R7 | IC AMP DIFF RF/IF 3.3GHZ 16LFCSP |
| ADL5565ACPZ-R7 | IC AMP DIFF 6GHZ 16LFCSP |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADA4940-1ARZ-RL | 功能描述:IC DIFF ADC DVR 18BIT LN 8SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 放大器類型:通用 電路數(shù):2 輸出類型:滿擺幅 轉(zhuǎn)換速率:1.8 V/µs 增益帶寬積:6.5MHz -3db帶寬:4.5MHz 電流 - 輸入偏壓:5nA 電壓 - 輸入偏移:100µV 電流 - 電源:65µA 電流 - 輸出 / 通道:35mA 電壓 - 電源，單路/雙路(±):1.8 V ~ 5.25 V，±0.9 V ~ 2.625 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-MSOP 包裝:管件 |
| ADA4940-1XCPZ-R7 | 制造商:Analog Devices 功能描述: |
| ADA4940-2 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Ultralow Power, Low Distortion |
| ADA4940-2ACP-EBZ | 制造商:Analog Devices 功能描述:EVAL BOARD DUAL DIFFERENTIAL 制造商:Analog Devices 功能描述:ADA4940-2, DIFF AMP, EVAL BOARD |
| ADA4940-2ACPZ-R2 | 制造商:Analog Devices 功能描述:SUB 10M W ADC DRIVER FOR PULSAR FAMILY - Tape and Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。