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参数资料
| 型号： | AD5251EVAL |
| 厂商： | Analog Devices, Inc. |
| 英文描述： | Memory Card Socket; No. of Contacts:50; Leaded Process Compatible:Yes; Mounting Type:Surface Mount; Peak Reflow Compatible (260 C):Yes; Gender:Male; No. of Rows:1; Width:31.60mm RoHS Compliant: Yes |
| 中文描述： | 双64和256位非易失性存储器的I2C数字电位器 |
| 文件页数： | 20/28页 |
| 文件大小： | 859K |
| 代理商： | AD5251EVAL |
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AD5251/AD5252
OPERATIONAL OVERVIEW
The AD5251/AD5252 are dual-channel digital potentiometers
in 1 k, 10 k, 50 k, or 100 k that allow 64 and 256 linear
resistance step adjustments. The AD5251/AD5252 employ
double-gate CMOS EEPROM technology that allows resistance
settings and user-defined data to be stored in the EEMEM
registers. The EEMEM is nonvolatile, such that settings remain
when power is removed. The RDAC wiper settings are restored
from the non-volatile
memory settings during device power-up
and can also be restored at any time during operation.
Rev. 0 | Page 20 of 28
The AD5251/AD5252 resistor wiper positions are determined
by the RDAC register contents. The RDAC register acts like a
scratch-pad register, allowing unlimited changes of resistance
settings. RDAC register contents can be changed using the
device’s serial I
2
C interface. The format of the data-words and
the commands to program the RDAC registers are discussed in
the I2C Interface Detail Description section.
The four RDAC registers have corresponding EEMEM memory
locations that provide nonvolatile storage of resistor wiper
position settings. The AD5251/AD5252 provide commands to
store the RDAC register contents to their respective EEMEM
memory locations. During subsequent power-on sequences, the
RDAC registers are automatically loaded with the stored value.
Whenever the EEMEM write operation is enabled, the device
activates the internal charge pump and raises the EEMEM cell
gate bias voltage to a high level, essentially erasing the current
content in the EEMEM register and allowing subsequent stor-
age of the new content. Saving data to an EEMEM register con-
sumes about 35 mA of current and lasts about 26 ms. Because
of charge pump operation, all RDAC channels may experience
noise coupling during the EEMEM writing operation.
The EEMEM restore time in power-up or during operation is
about 300 μs. Note that the power up EEMEM refresh time
depends on how fast V
DD
reaches its final value. As a result, any
supply voltage decoupling capacitors limit the EEMEM restore
time during power-up. Figure 32 shows the power up profile
where V
DD
, without any decoupling capacitors connected to it,
is applied with a digital signal. The device initially resets the
measured RDACs to midscale before reaching their final values
during EEMEM restoration.
In addition, users should issue a NOP Command 0 immediately
after using Command 1 to restore the EEMEM setting to
RDAC, to minimize supply current dissipation. Directly reading
user data from EEMEM does not require similar NOP
command execution.
In addition to the movement of data between RDAC registers
and EEMEM memory, the AD5251/AD5252 provide other
shortcut commands that facilitate the users’ programming
needs, as shown in Table 11.
Table 11. AD5251/AD5252 Quick Commands
Commmand
Description
0
NOP
1
Restore EEMEM content to RDAC. User should
issue NOP immediately after this command to
conserve power.
2
Store RDAC register setting to EEMEM.
3
Decrement RDAC 6 dB (shift data bits right).
4
Decrement all RDACs 6 dB (shift all data bits
right).
5
Decrement RDAC one step.
6
Decrement all RDACs one step.
7
Reset EEMEM contents to all RDACs.
8
Increment RDAC 6 dB (shift data bits left).
9
Increment All RDACs 6 dB (shift all data bits left).
10
Increment RDAC one step.
11
Increment all RDACs one step.
12–15
Reserved.
LINEAR INCREMENT AND DECREMENT
COMMANDS
The increment and decrement commands (10, 11, 5, and 6) are
useful for linear step adjustment applications. These commands
simplify microcontroller software coding by allowing the
controller to send just an increment or decrement command to
the AD5251/AD5252. The adjustments can be directed to an
individual RDAC or to all four RDACs.
±6 dB ADJUSTMENTS (DOUBLING/HALVING
WIPER SETTING)
The AD5251/AD5252 accommodates ±6 dB adjustments of the
RDAC wiper positions by shifting the register contents to
left/right for increment/decrement operations, respectively.
Commands 3, 4, 8, and 9 can be used to increment or
decrement the wiper positions in 6 dB steps synchronously or
asynchronously.
Incrementing the wiper position by +6 dB is essentially
doubling the RDAC register value, while decrementing by
–6 dB is halving the register content. Internally, the
AD5251/AD5252 use shift registers to shift the bits left and
right to achieve a ±6 dB increment or decrement. The
maximum number of adjustments is nine and eight steps for
increment from zero scale and decrement from full scale,
respectively. These functions are useful for various audio/video
level adjustments, especially for white LED brightness settings
where human visual responses are more sensitive to large than
small adjustments.
相关PDF资料 |
PDF描述 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD5252 | 制造商:AD 制造商全称:Analog Devices 功能描述:Dual 64-and 256-Position I2C Nonvolatile Memory Digital Potentiometers |
| AD5252BRU1 | 功能描述:IC DIG POT DUAL 256 1K 14-TSSOP RoHS:否 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) |
| AD5252BRU10 | 功能描述:IC DIG POT DUAL 256 10K 14TSSOP RoHS:否 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) |
| AD5252BRU100 | 功能描述:IC DIG POT DUAL 256 100K 14TSSOP RoHS:否 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) |
| AD5252BRU100-RL7 | 功能描述:IC DCP DUAL 100K 256POS 14TSSOP RoHS:否 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) |
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