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參數資料
| 型號： | DAC8408GP |
| 廠商： | PRECISION MONOLITHICS INC |
| 元件分類： | DAC |
| 英文描述： | Quad 8-Bit Multiplying CMOS D/A Converter with Memory |
| 中文描述： | 8-BIT DAC, PDIP28 |
| 文件頁數： | 8/16頁 |
| 文件大?。?/td> | 217K |
| 代理商： | DAC8408GP |
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)
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相關代理商/技術參數 |
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| DAC8408GPZ | 功能描述:IC DAC 8BIT QUAD W/MEMORY 28DIP RoHS:是 類別:集成電路 (IC) >> 數據采集 - 數模轉換器 系列:- 產品培訓模塊:Data Converter Fundamentals DAC Architectures 標準包裝:750 系列:- 設置時間:7µs 位數:16 數據接口:并聯(lián) 轉換器數目:1 電壓電源:雙 ± 功率耗散（最大）:100mW 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-LCC（J 形引線） 供應商設備封裝:28-PLCC（11.51x11.51） 包裝:帶卷 (TR) 輸出數目和類型:1 電壓，單極；1 電壓，雙極 采樣率（每秒）:143k |
| DAC8408HP | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Analog Devices 功能描述: |
| DAC8411 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:1.8V to 5.5V, 80mA, 14- and 16-Bit, Low-Power, Single-Channel,DIGITAL-TO-ANALOG CONVERTERS in SC70 Package |
| DAC8411EVM | 功能描述:數據轉換 IC 開發(fā)工具 DAC8411 Eval Mod RoHS:否 制造商:Texas Instruments 產品:Demonstration Kits 類型:ADC 工具用于評估:ADS130E08 接口類型:SPI 工作電源電壓:- 6 V to + 6 V |
| DAC8411EVM | 制造商:Texas Instruments 功能描述:Development Tool |
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