AD5255_15 Datasheet, PDF (1/20 Pages) Analog Devices – 3-Channel Digital Potentiometer with Nonvolatile Memory

3-Channel Digital Potentiometer with
Nonvolatile Memory
AD5255
FEATURES
3 channels
Dual 512 position
Single 128 position
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
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 controls
White LED brightness adjustment
Programmable gain and offset controls
Programmable filters
GENERAL DESCRIPTION
The AD5255 provides a 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 VR. 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.
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.
FUNCTIONAL BLOCK DIAGRAM
V_DD
V_SS
GND
SCL
SDA
A0_RDAC
A1_RDAC
A0_E
A1_E
RS
WP
I²C
SERIAL
INTERFACE
POWER-ON
RESET
256 BYTES
USER
EEPROM
32 BYTES
RDAC
EEPROM
DATA
CONTROL
COMMAND
DECODE
LOGIC
ADDRESS
DECODE
LOGIC
DECODE
LOGIC
RDAC0
A0
W0
B0
9-BIT
RDAC1
A1
W1
B1
9-BIT
RDAC2
A2
W2
B2
7-BIT
Figure 1.
Additional features of the AD5255 include preprogrammed
linear and logarithmic increment/decrement wiper changing.
The actual resistor tolerances are stored in EEPROM, so the
actual end-to-end resistance is known, which is valuable for
calibration in precision applications.
The AD5255 is available in a 24-lead TSSOP. All parts are
guaranteed to operate over the extended industrial temperature
range of −40°C to +85°C
1 _{The terms programmable resistor, variable resistor, RDAC, and digital}
potentiometer are used interchangeably.
2 _{The terms nonvolatile memory, EEMEM, and EEPROM are used}
interchangeably.
Rev. A
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