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| 型号： | AD8400ARZ1-REEL |
| 厂商： | Analog Devices Inc |
| 文件页数： | 14/32页 |
| 文件大小： | 0K |
| 描述： | IC POT DGTL 8BIT SGL 1K 8SOIC |
| 标准包装： | 2,500 |
| 接片： | 256 |
| 电阻（欧姆）： | 1k |
| 电路数： | 1 |
| 温度系数： | 标准值 500 ppm/°C |
| 存储器类型： | 易失 |
| 接口： | 3 线 SPI（芯片选择） |
| 电源电压： | 2.7 V ~ 5.5 V |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SO |
| 包装： | 带卷 (TR) |
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AD8400/AD8402/AD8403
Rev. E | Page 21 of 32
Like a mechanical potentiometer, RDAC is symmetrical. The
resistance between the Wiper W and Terminal A also produces
a digitally controlled complementary resistance, RWA. When
these terminals are used, the B terminal can be tied to the wiper
or left floating. RWA starts at the maximum and decreases as the
data loaded into the RDAC latch increases. The general transfer
equation for this RWA is
()
W
AB
WA
R
D
R
+
×
=
256
(3)
where D is the data loaded into the 8-bit RDAC# latch, and RAB
is the nominal end-to-end resistance.
For example, when the B terminal is either open-circuited or
tied to the Wiper W, the following RDAC latch codes result in
the following RWA (for the 10 kΩ version):
Table 11.
D (Dec)
RWA (
)
Output State
255
89
Full-Scale
128
5,050
Midscale (RS = 0 Condition)
1
10,011
1 LSB
0
10,050
Zero-Scale
The typical distribution of RAB from channel to channel
matches within ±1%. However, device-to-device matching
is process lot dependent and has a ±20% variation. The tem-
perature coefficient, or the change in RAB with temperature,
is 500 ppm/°C.
The wiper-to-end-terminal resistance temperature coefficient
has the best performance over the 10% to 100% of adjustment
range where the internal wiper contact switches do not con-
tribute any significant temperature related errors. The graph in
the potentiometer with codes below 32 results in the larger
temperature coefficients plotted.
PROGRAMMING THE POTENTIOMETER DIVIDER
Voltage Output Operation
The digital potentiometer easily generates an output voltage
proportional to the input voltage applied to a given terminal.
For example, connecting the A terminal to 5 V and the B termi-
nal to ground produces an output voltage at the wiper starting
at 0 V up to 1 LSB less than 5 V. Each LSB is equal to the voltage
applied across the A to B terminals divided by the 256-position
resolution of the potentiometer divider. The general equation
defining the output voltage with respect to ground for any given
input voltage applied to the A to B terminals is
B
AB
W
V
D
V
+
×
=
256
(4)
Operation of the digital potentiometer in the voltage divider
mode results in more accurate operation over temperature.
Here the output voltage is dependent on the ratio of the internal
resistors, not the absolute value; therefore, the temperature drift
improves to 15 ppm/°C.
At the lower wiper position settings, the potentiometer divider
temperature coefficient increases because the contribution of
the CMOS switch wiper resistance becomes an appreciable
portion of the total resistance from the B terminal to the
Wiper W. See Figure 17 for a plot of potentiometer tempco
performance vs. code setting.
DIGITAL INTERFACING
The AD8400/AD8402/AD8403 contain a standard SPI-
compatible, 3-wire, serial input control interface. The three
inputs are clock (CLK), chip select (CS), and serial data input
(SDI). The positive-edge sensitive CLK input requires clean
transitions to avoid clocking incorrect data into the serial input
register. For the best result, use logic transitions faster than
1 V/μs. Standard logic families work well. If mechanical switches
are used for product evaluation, they should be debounced by
a flip-flop or other suitable means. The block diagrams in
, and
show the internal digital
circuitry in more detail. When
CS is taken active low, the clock
loads data into the 10-bit serial register on each positive clock
edge (see
).
RDAC
LATCH
NO. 1
GND
A1
W1
B1
VDD
AD8400
CS
CLK
8
D7
D0
EN
ADDR
DEC
A1
A0
SDI
DI
D0
D7
10-BIT
SER
REG
0
10
92
-0
45
Figure 46. AD8400 Block Diagram
RDAC
LATCH
NO. 1
R
AGND
RS
A1
W1
B1
VDD
AD8402
CS
CLK
D7
D0
RDAC
LATCH
NO. 2
R
A4
W4
B4
D7
D0
EN
ADDR
DEC
A1
A0
SDI
DI
10-BIT
SER
REG
D0
SHDN
DGND
D7
8
01
09
2-
04
6
Figure 47. AD8402 Block Diagram
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD8400ARZ50 | 功能描述:IC POT DGTL 8BIT SGL 50K 8-SOIC RoHS:是 类别:集成电路 (IC) >> 数据采集 - 数字电位器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- 接片:256 电阻（欧姆）:100k 电路数:1 温度系数:标准值 35 ppm/°C 存储器类型:非易失 接口:3 线串口 电源电压:2.7 V ~ 5.25 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-WDFN 裸露焊盘 供应商设备封装:8-TDFN-EP（3x3） 包装:剪切带 (CT) 产品目录页面:1399 (CN2011-ZH PDF) 其它名称:MAX5423ETA+TCT |
| AD8400ARZ50-REEL | 功能描述:IC POT DGTL 8BIT 50K 1CH 8SOIC RoHS:是 类别:集成电路 (IC) >> 数据采集 - 数字电位器 系列:- 标准包装:3,000 系列:DPP 接片:32 电阻（欧姆）:10k 电路数:1 温度系数:标准值 300 ppm/°C 存储器类型:非易失 接口:3 线串行（芯片选择，递增，增/减） 电源电压:2.5 V ~ 6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-WFDFN 裸露焊盘 供应商设备封装:8-TDFN（2x3） 包装:带卷 (TR) |
| AD8401 | 制造商:AD 制造商全称:Analog Devices 功能描述:8-Bit, 4-Channel Data Acquisition System |
| AD8401AR | 制造商:Rochester Electronics LLC 功能描述:8-BIT,4-CHANNEL A/D CONV - Bulk 制造商:Analog Devices 功能描述: |
| AD8401ARZ | 制造商:Analog Devices 功能描述:DATA ACQ SYS SGL ADC SGL DAC 8BIT 28SOIC - Rail/Tube |
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