AD5251_12 Datasheet, PDF (1/28 Pages) Analog Devices – Dual 64-/256-Position I2C Nonvolatile Memory Digital Potentiometers

Data Sheet
Dual 64-/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 asynchronous dual-channel update
Wiper setting readback
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, T_A = 55°C
Operating temperature: –40°C to +105°C
APPLICATIONS
Mechanical potentiometer replacement
General-purpose DAC replacement
LCD panel V_COM adjustment
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
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 information, such as
memory data for other components, look-up table, or system
identification information.
FUNCTIONAL BLOCK DIAGRAM
V_DD
V_SS
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.
The AD5251/AD5252 allow the host I²C controllers to write
any of the 64-/256-step wiper settings in the RDAC registers
and store them in the EEMEM. Once the settings are stored,
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 mode. The
increment and decrement functions allow stepwise linear
adjustments, with a ± 6 dB step change 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 AD5251/AD5252 have a patented resistance-tolerance
storing function that allows 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. All parts are
guaranteed to operate over the –40°C to +105°C extended
industrial temperature range.
1 _{The terms nonvolatile memory and EEMEM are used interchangeably.}
2 _{The terms digital potentiometer and RDAC are used interchangeably.}
Rev. D
Document Feedback
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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] ©2004–2012 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com