參數(shù)資料
型號(hào)： DAC8408AT
廠商： ANALOG DEVICES INC
元件分類： DAC
英文描述： Quad 8-Bit Multiplying CMOS D/A Converter with Memory
中文描述： QUAD, PARALLEL, 8 BITS INPUT LOADING, 0.19 us SETTLING TIME, 8-BIT DAC, CDIP28
封裝： CERDIP-28
文件頁(yè)數(shù)： 8/16頁(yè)
文件大?。?/td> 217K
代理商： DAC8408AT
DAC8408
–8–
REV. A
CIRCUIT INFORMAT ION
T he DAC8408 combines four identical 8-bit CMOS DACs
onto a single monolithic chip. Each DAC has its own reference
input, feedback resistor, and on-board data latches. It also fea-
tures a read/write function that serves as an accessible memory
location for digital-input data words. T he DAC’s three-state
readback drivers place the data word back onto the data bus.
D/A CONVE RT E R SE CT ION
Each DAC contains a highly stable, silicon-chromium, thin-film,
R-2R resistor ladder network and eight pairs of current steering
switches. T hese switches are in series with each ladder resistor
and are single-pole, double-throw NMOS transistors; the gates
of these transistors are controlled by CMOS inverters. Figure 1
shows a simplified circuit of the R-2R resistor ladder section,
and Figure 2 shows an approximate equivalent switch circuit.
T he current through each resistor leg is switched between I
OUT 1
and I
OUT 2
. T his maintains a constant current in each leg, re-
gardless of the digital input logic states.
Each transistor switch has a finite “ON” resistance that can in-
troduce errors to the DAC’s specified performance. T hese resis-
tances must be accounted for by making the voltage drop across
each transistor equal to each other. T his is done by binarily-
scaling the transistor’s “ON” resistance from the most signifi-
cant bit (MSB) to the least significant bit (LSB). With 10 volts
applied at the reference input, the current through the MSB
switch is 0.5 mA, the next bit is 0.25 mA, etc.; this maintains a
constant 10 mV drop across each switch and the converter’s ac-
curacy is maintained. It also results in a constant resistance ap-
pearing at the DAC’s reference input terminal; this allows the
DAC to be driven by a voltage or current source, ac or dc of
positive or negative polarity.
Shown in Figure 3 is an equivalent output circuit for DAC A.
T he circuit is shown with all digital inputs high. T he leakage
current source is the combination of surface and junction leak-
ages to the substrate. T he 1/256 current source represents the
constant 1-bit current drain through the ladder terminating re-
sistor. T he situation is reversed with all digital inputs low, as
shown in Figure 4. T he output capacitance is code dependent,
and therefore, is modulated between the low and high values.
Figure 1. Simplified D/A Circuit of DAC8408
Figure 2. N-Channel Current Steering Switch
Figure 3. Equivalent DAC Circuit (AII Digital Inputs HIGH)
相關(guān)PDF資料
PDF描述
DAC8408BT Quad 8-Bit Multiplying CMOS D/A Converter with Memory
DAC8408ET Quad 8-Bit Multiplying CMOS D/A Converter with Memory
DAC8408FP Quad 8-Bit Multiplying CMOS D/A Converter with Memory
DAC8408FPC Quad 8-Bit Multiplying CMOS D/A Converter with Memory
DAC8408FS Quad 8-Bit Multiplying CMOS D/A Converter with Memory
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DAC8408AT/883 制造商:未知廠家 制造商全稱:未知廠家 功能描述:8-Bit Digital-to-Analog Converter
DAC8408AT/883C 功能描述:數(shù)模轉(zhuǎn)換器- DAC QUAD 8-BIT CMOS DAC-LEV.B RoHS:否 制造商:Texas Instruments 轉(zhuǎn)換器數(shù)量:1 DAC 輸出端數(shù)量:1 轉(zhuǎn)換速率:2 MSPs 分辨率:16 bit 接口類型:QSPI, SPI, Serial (3-Wire, Microwire) 穩(wěn)定時(shí)間:1 us 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-14 封裝:Tube
DAC8408AT2 制造商:AD 制造商全稱:Analog Devices 功能描述:Quad 8-Bit Multiplying CMOS D/A Converter with Memory
DAC8408BIET 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Analog Devices 功能描述:
DAC8408BIGP 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Analog Devices 功能描述:
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