参数资料
型号: DAC8408BT
厂商: PRECISION MONOLITHICS INC
元件分类: DAC
英文描述: Quad 8-Bit Multiplying CMOS D/A Converter with Memory
中文描述: 8-BIT DAC, CDIP28
文件页数: 8/16页
文件大小: 217K
代理商: DAC8408BT
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)
相关PDF资料
PDF描述
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
DAC8408FT Quad 8-Bit Multiplying CMOS D/A Converter with Memory
相关代理商/技术参数
参数描述
DAC8408BT2 制造商:AD 制造商全称:Analog Devices 功能描述:Quad 8-Bit Multiplying CMOS D/A Converter with Memory
DAC8408BTC/883C 制造商:Analog Devices 功能描述:DAC 制造商:Rochester Electronics LLC 功能描述:QUAD 8-BIT MULT DAC-LEV.B - Bulk
DAC8408ET 制造商:Analog Devices 功能描述:
DAC8408FP 功能描述:IC DAC 8BIT QUAD W/MEMORY 28-DIP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:- 产品培训模块:Data Converter Fundamentals DAC Architectures 标准包装:750 系列:- 设置时间:7µs 位数:16 数据接口:并联 转换器数目:1 电压电源:双 ± 功率耗散(最大):100mW 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:28-LCC(J 形引线) 供应商设备封装:28-PLCC(11.51x11.51) 包装:带卷 (TR) 输出数目和类型:1 电压,单极;1 电压,双极 采样率(每秒):143k
DAC8408FPC 功能描述:IC DAC 8BIT QUAD W/MEMORY 28PLCC RoHS:否 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:- 产品培训模块:Data Converter Fundamentals DAC Architectures 标准包装:750 系列:- 设置时间:7µs 位数:16 数据接口:并联 转换器数目:1 电压电源:双 ± 功率耗散(最大):100mW 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:28-LCC(J 形引线) 供应商设备封装:28-PLCC(11.51x11.51) 包装:带卷 (TR) 输出数目和类型:1 电压,单极;1 电压,双极 采样率(每秒):143k