AD5251(Rev0) データシートの表示（PDF） - Analog Devices

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AD5251
(Rev.:Rev0)

Dual 64-and 256-Position I2C Nonvolatile Memory Digital Potentiometers

Analog Devices 

Dual 64-and 256-Position I2C Nonvolatile

Memory Digital Potentiometers

AD5251/AD5252

FEATURES

AD5251: Dual 64-position resolution

AD5252: Dual 256-position resolution

1 kΩ, 10 kΩ, 50 kΩ, 100 kΩ

Nonvolatile memory1 stores wiper setting w/write protection

Power-on refreshed with EEMEM settings in 300 µs typ

EEMEM rewrite time = 540 µs typ

Resistance tolerance stored in nonvolatile memory

12 extra bytes in EEMEM for user-defined information

I2C compatible serial interface

Direct read/write access of RDAC2 and EEMEM registers

Predefined linear increment/decrement commands

Predefined ±6 dB step change commands

Synchronous or aysynchronous dual channel update

Wiper setting read back

4 MHz bandwidth—1 kΩ version

Single supply 2.7 V to 5.5 V

Dual supply ±2.25 V to ±2.75 V

2 slave address decoding bits allow operation of 4 devices

100-year typical data retention TA = 55°C

Operating temperature –40°C to +85°C

APPLICATIONS

Mechanical potentiometer replacement

General purpose DAC replacement

LCD panel VCOM adjustment

GENERAL DESCRIPTION

The AD5251/AD5252 are dual-channel, I2C, nonvolatile mem-

ory, digitally controlled potentiometers with 64/256 positions,

respectively. These devices perform the same electronic adjust-

ment functions as mechanical potentiometers, trimmers, and

variable resistors. The parts’ versatile programmability allows

multiple modes of operation, including read/write access in the

RDAC and EEMEM registers, increment/decrement of

resistance, resistance changes in ±6 dB scales, wiper setting

readback, and extra EEMEM for storing user-defined infor-

mation such as memory data for other components, look-up

table, or system identification information.

The AD5251/AD5252 allow the host I2C controllers to write

any of the 64- or 256-step wiper settings in the RDAC registers

and store them in the EEMEM. Once the settings are stored,

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable.

However, no responsibility is assumed by Analog Devices for its use, nor for any

infringements of patents or other rights of third parties that may result from its use.

Specifications subject to change without notice. No license is granted by implication

or otherwise under any patent or patent rights of Analog Devices. Trademarks and

registered trademarks are the property of their respective owners.

White LED brightness adjustment

RF base station power amp bias control

Programmable gain and offset control

Programmable voltage-to-current conversion

Programmable power supply

Sensor calibrations

FUNDAMENTAL BLOCK DIAGRAM

VDD

VSS

DGND

WP

SCL

SDA

AD0

AD1

I2C

SERIAL

INTERFACE

POWER-

ON RESET

RDAC EEMEM

EEMEM

POWER-ON

REFRESH

RAB

TOL

RDAC1

REGIS-

TER

RDAC1 A1

W1

B1

DATA

CONTROL

RDAC3

REGIS-

TER

COMMAND

DECODE LOGIC

RDAC3 A3

W3

B3

ADDRESS

DECODE LOGIC

CONTROL LOGIC

AD5251/

AD5252

Figure 1.

1The terms nonvolatile memory and EEMEM are used interchangeably.

2The terms digital potentiometer and RDAC are used interchangeably.

they are restored automatically to the RDAC registers at system

power-on; the settings can also be restored dynamically.

The AD5251/AD5252 provide additional increment,

decrement, +6 dB step change, and –6 dB step change in

synchronous or asynchronous channel update modes. The

increment and decrement functions allow stepwise linear

adjustments, while ±6 dB step changes are equivalent to

doubling or halving the RDAC wiper setting. These functions

are useful for steep-slope nonlinear adjustments such as white

LED brightness and audio volume control. The parts have a

patented resistance tolerance storing function which enable the

user to access the EEMEM and obtain the absolute end-to-end

resistance values of the RDACs for precision applications.

The AD5251/AD5252 are available in TSSOP-14 packages in

1 kΩ, 10 kΩ, 50 kΩ, and 100 kΩ options and all parts can

operate over the –40°C to +85°C extended industrial

temperature range.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

www.analog.com

Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.

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