Dual 64-/256-Position I2C Nonvolatile
Memory Digital Potentiometers
Data Sheet
Rev. D
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FEATURES
AD5251: Dual 64-position resolution
AD5252: Dual 256-position resolution
1 k, 10 k, 50 k, 100 k
Nonvolatile memory1 stores wiper setting w/write protection Power-on refreshed with EEMEM settings in 300 s typ
EEMEM rewrite time = 540 s 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 k 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
RDAC1
REGIS-
TER
RDAC3
REGIS-
TER
RDAC1
RDAC3
DATA
CONTROL
COMMAND
DECODE LOGIC
ADDRESS
DECODE LOGIC
CONTROL LOGIC
AD5251/
AD5252
I2C
SERIAL
INTERFACE
POWER-
ON RESET
VDD
A1
W1
B1
A3
W3
B3
VSS
DGND
SCL
SDA
AD0
AD1
WP
RDAC EEMEM
RAB
TOL
03823-0-001
EEMEM
POWER-ON
REFRESH
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 k, 10 k, 50 k, and 100 k 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.