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参数资料
| 型号： | AD7248ATQ |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | DAC |
| 英文描述： | LC2MOS 12-Bit DACPORTs |
| 中文描述： | PARALLEL, WORD INPUT LOADING, 12-BIT DAC, CDIP20 |
| 封装： | 0.300 INCH, GLASS SEALED, CERDIP-20 |
| 文件页数： | 9/16页 |
| 文件大小： | 306K |
| 代理商： | AD7248ATQ |
AD7245A/AD7248A
REV. A
–9–
T he data held in the DAC latch determines the analog output of
the converter. Data is latched into the DAC latch on the rising
edge of
LDAC
. T his
LDAC
signal is an asynchronous signal
and is independent of
WR
. T his is useful in many applications.
However, in systems where the asynchronous
LDAC
can occur
during a write cycle (or vice versa) care must be taken to ensure
that incorrect data is not latched through to the output. For ex-
ample, if
LDAC
goes LOW while
WR
is “LOW”, then the
LDAC
signal must stay LOW for t
7
or longer after
WR
goes
high to ensure correct data is latched through to the output.
T able I. AD7245A T ruth T able
CLR
LDAC WR
CS
Function
H
H
H
H
H
H
H
L
g
L
H
H
H
H
L
g
X
H
L
H
X
L
g
H
H
X
H
L
X
H
L
L
H
H
X
H
Both Latches are T ransparent
Both Latches are Latched
Both Latches are Latched
Input Latches T ransparent
Input Latches Latched
DAC Latches T ransparent
DAC Latches Latched
DAC Latches Loaded with all 0s
DAC Latches Latched with All
0s and Output Remains at
0 V or –5 V
Both Latches are T ransparent
and Output Follows Input Data
g
L
L
L
H = High State L = Low State X = Don’t Care
T he contents of the DAC latch are reset to all 0s by a low level
on the
CLR
line. With both latches transparent, the
CLR
line
functions like a zero override with the output brought to 0 V in
the unipolar mode and –5 V in the bipolar mode for the dura-
tion of the
CLR
pulse. If both latches are latched, a “LOW”
pulse on the
CLR
input latches all 0s into the DAC latch and
the output remains at 0 V (or –5 V) after the
CLR
line has re-
turned “HIGH.” T he
CLR
line can be used to ensure powerup
to 0 V on the AD7245A output in unipolar operation and is also
useful, when used as a zero override, in system calibration
cycles.
Figure 4 shows the input control logic for the AD7245A and the
write cycle timing for the part is shown in Figure 5.
Figure 4. AD7245A Input Control Logic
Figure 5. AD7245A Write Cycle Timing Diagram
INT E RFACE LOGIC INFORMAT ION—AD7248A
T he input loading structure on the AD7248A is configured for
interfacing to microprocessors with an 8-bit wide data bus. T he
part contains two 12-bit latches—an input latch and a DAC
latch. Only the data held in the DAC latch determines the ana-
log output from the converter. T he truth table for AD7248A
operation is shown in T able II, while the input control logic dia-
gram is shown in Figure 6.
Figure 6. AD7248A Input Control Logic
CSMSB
,
CSLSB
and
WR
control the loading of data from the
external data bus to the input latch. T he eight data inputs on
the AD7248A accept right justified data. T his data is loaded to
the input latch in two separate write operations.
CSLSB
and
WR
control the loading of the lower 8-bits into the 12-bit wide
latch. T he loading of the upper 4-bit nibble is controlled by
CSMSB
and
WR
. All control inputs are level triggered, and in-
put data for either the lower byte or upper 4-bit nibble is latched
into the input latches on the rising edge of
WR
(or either
CSMSB
or
CSLSB
). T he order in which the data is loaded to
the input latch (i.e., lower byte or upper 4-bit nibble first) is not
important.
T he
LDAC
input controls the transfer of 12-bit data from the
input latch to the DAC latch. T his
LDAC
signal is also level
triggered, and data is latched into the DAC latch on the rising
edge of
LDAC
. T he
LDAC
input is asynchronous and indepen-
dent of
WR
. T his is useful in many applications especially in
相关PDF资料 |
PDF描述 |
|---|---|
| AD7248JN | CAP CERM 15000PF 50V X7R 10%0805 |
| AD7248JP | CAPACITOR, 0805 33NF 50V CAPACITOR, 0805 33NF 50V; CAPACITANCE:33000PF; VOLTAGE RATING, DC:50V; CAPACITOR DIELECTRIC TYPE:CERAMIC MULTI-LAYER; SERIES:B37941; TOLERANCE, :10%; TOLERANCE, -:10%; TEMP, OP. MAX:125(DEGREE C); TEMP, OP. RoHS Compliant: Yes |
| AD7245 | LC2MOS 12-Bit DACPORT |
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| AD7245JN | LC2MOS 12-Bit DACPORT |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AD7248ATQ3 | 制造商:AD 制造商全称:Analog Devices 功能描述:LC2MOS 12-Bit DACPORTs |
| AD7248JN | 功能描述:IC DAC 12BIT W/REF 20-DIP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:DACPORT® 标准包装:2,400 系列:- 设置时间:- 位数:18 数据接口:串行 转换器数目:3 电压电源:模拟和数字 功率耗散（最大）:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:36-TFBGA 供应商设备封装:36-TFBGA 包装:带卷 (TR) 输出数目和类型:* 采样率（每秒）:* |
| AD7248JNZ | 功能描述:IC DAC 12BIT W/REF 20-DIP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:DACPORT® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:50 系列:- 设置时间:4µs 位数:12 数据接口:串行 转换器数目:2 电压电源:单电源 功率耗散（最大）:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-uMAX 包装:管件 输出数目和类型:2 电压，单极 采样率（每秒）:* 产品目录页面:1398 (CN2011-ZH PDF) |
| AD7248JP | 制造商:Rochester Electronics LLC 功能描述:12-BIT CMOS VOUT DACPORT - Bulk |
| AD7248JP-REEL | 功能描述:IC DAC 12BIT W/REF 28-PLCC T/R RoHS:否 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:DACPORT® 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 |
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