3-Channel Digital Potentiometer with
Nonvolatile Memory
AD5255
FEATURES
FUNCTIONAL BLOCK DIAGRAM
3 channels:
Dual 512-position
Single 128-position
256 BYTES
USER
EEPROM
RDAC0
V
DD
A0
W0
B0
V
SS
32 BYTES
RDAC
EEPROM
GND
25 kΩ or 250 kΩ full-scale resistance
Low temperature coefficient:
Potentiometer divider 15 ppm/°C
Rheostat mode 35 ppm/°C
Nonvolatile memory retains wiper settings
Permanent memory write protection
Linear increment/decrement
6 dB increment/decrement
I2C-compatible serial interface
2.7 V to 5.5 V single-supply operation
2.25 V to 2.75 V dual-supply operation
Power-on reset time
9 BIT
SCL
SDA
RDAC1
DATA
CONTROL
2
I C
A1
W1
B1
SERIAL
INTERFACE
A0_RDAC
A1_RDAC
A0_E
9 BIT
COMMAND
DECODE
LOGIC
A1_E
RDAC2
A2
W2
B2
POWER-ON
RESET
ADDRESS
DECODE
LOGIC
RS
7 BIT
DECODE
LOGIC
WP
Figure 1.
256 bytes general-purpose user EEPROM
11 bytes RDAC user EEPROM
GBIC and SFP compliant EEPROM
100-year typical data retention at TA = 55°C
APPLICATIONS
Mechanical potentiometer replacement
RGB LED backlight control
White LED brightness adjustment
Programmable gain and offset control
Programmable filters
GENERAL DESCRIPTION
Additional features of the AD5255 include preprogrammed
linear and logarithmic increment/decrement wiper changing.
The actual resistor tolerances are stored in EEPROM so that the
actual end-to-end resistance is known, which is valuable for
calibration in precision applications.
The AD5255 provides dual 512-position and a single
128-position digitally controlled variable resistors1 (VR) in a
TSSOP package. This device performs the same electronic
adjustment function as a potentiometer, trimmer, or variable
resistor. Each VR offers a completely programmable value of
resistance between the A terminal and the wiper or the B
terminal and the wiper. The fixed A-to-B terminal resistance of
25 kΩ or 250 kΩ has a 1% channel-to-channel matching
tolerance and a nominal temperature coefficient of 35 ppm/°C.
The AD5255 is available in a 24-lead TSSOP package. All parts
are guaranteed to operate over the extended industrial tempera-
ture range of −40°C to +85°C.
1 The terms programmable resistor, variable resistor, RDAC, and digital
potentiometer are used interchangeably.
Wiper position programming, EEPROM2 reading, and EEPROM
writing is conducted via the standard 2-wire I2C interface. Pre-
vious/default wiper position settings can be stored in memory,
and refreshed upon system power-up.
2 The terms nonvolatile memory, EEMEM, and EEPROM are used
interchangeably.
Rev. 0
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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
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