数据搜索系统,热门电子元器件搜索
  Chinese▼

Delete All
ON OFF
ALLDATASHEETCN.COM

X  

预览 PDF Download HTML

DAC7821 Datasheet(数据表) 11 Page - Texas Instruments

Click here to check the latest version.
部件型号  DAC7821
说明  12-Bit, Parallel Input, Multiplying Digital-to-Analog Converter
下载  18 Pages
Scroll/Zoom Zoom In 100% Zoom Out
制造商  TI [Texas Instruments]
网页  http://www.ti.com
标志 

DAC7821 Datasheet(HTML) 11 Page - Texas Instruments

Zoom Inzoom in Zoom Outzoom out
 11 page
background image
www.ti.com
THEORY OF OPERATION
R
R
R
R
2R
2R
2R
2R
2R
DB0
(LSB)
DB9
DB10
DB11
(MSB)
I
1
OUT
R
FB
V
REF
I
2
OUT
)(V
OUT
+ ) VREF
CODE
4096
(1)
OPA277
DAC7821
15V
V+
V-
-15V
GND
I
1
OUT
R
FB
V
REF
V
DD
V
DD
V
OUT
I
2
OUT
DAC7821
SBAS365A – OCTOBER 2005 – REVISED FEBRUARY 2006
The DAC7821 is a single channel current output, 12-bit digital-to-analog converter (DAC). The architecture,
illustrated in Figure 25, is an R-2R ladder configuration with the three MSBs segmented. Each 2R leg of the
ladder is either switched to IOUT1 or the IOUT2 terminal. The IOUT1 terminal of the DAC is held at a virtual GND
potential by the use of an external I/V converter op amp. The R-2R ladder is connected to an external reference
input VREF that determines the DAC full-scale current. The R-2R ladder presents a code-independent load
impedance to the external reference of 10 k
Ω ±20%. The external reference voltage can vary over a range of
–15 V to +15 V, thus providing bipolar IOUT current operation. By using an external I/V converter and the
DAC7821 RFB resistor, output voltage ranges of –VREF to VREF can be generated.
Figure 25. Equivalent R-2R DAC Circuit
When using an external I/V converter and the DAC7821 RFB resistor, the DAC output voltage is given by
Equation 1:
Each DAC code determines the 2R leg switch position to either GND or IOUT. Because the DAC output
impedance as seen looking into the IOUT1 terminal changes versus code, the external I/V converter noise gain
will also change. Because of this, the external I/V converter op amp must have a sufficiently low offset voltage
such that the amplifier offset is not modulated by the DAC IOUT1 terminal impedance change. External op amps
with large offset voltages can produce INL errors in the transfer function of the DAC7821 as a result of offset
modulation versus DAC code.
For best linearity performance of the DAC7821, an op amp with a low input offset voltage (OPA277) is
recommended (see Figure 26). This circuit allows VREF swinging from –10 V to +10 V.
Figure 26. Voltage Output Configuration
11




HTML 页

1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18 


数据表 下载




链接网址


Privacy Policy
ALLDATASHEETCN.COM
ALLDATASHEET是否为您带来帮助?  [ DONATE ]  

关于 Alldatasheet    |   广告服务   |   联系我们   |   隐私政策   |   书签   |   链接交换   |   制造商名单
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  , Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp  |   Russian : Alldatasheetru.com
Korean : Alldatasheet.co.kr   |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com  |   Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl