AD5255BRU250-RL7 Analog Devices Inc, AD5255BRU250-RL7 Datasheet - Page 16

• Manufacturer Part Number: AD5255BRU250-RL7
• Manufacturer: Analog Devices Inc

Specifications of AD5255BRU250-RL7

• Number Of Elements: 3
• Resistance (max): 250KOhm
• Power Supply Requirement: Single/Dual
• Interface Type: Serial (2-Wire/I2C)
• Single Supply Voltage (typ): 5V
• Dual Supply Voltage (typ): ±2.5V
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (min): ±2.2V
• Dual Supply Voltage (max): ±2.7V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 24
• Lead Free Status / RoHS Status: Not Compliant

AD5255
USING ADDITIONAL INTERNAL
NONVOLATILE EEPROM
The AD5255 contains additional internal user EEPROM for
saving constants and other data. The user EEPROM I
word follows the same format as the general-purpose EEPROM
memory shown in Figure 19 and Figure 20. User EEPROM
memory addresses are shown in Table 6.
To support the use of multiple EEPROM modules on a single
I
Pin 21 and Pin 22 (A1_EE and A0_EE), to manually set the
address of the EEPROM included with the AD5255. This
feature ensures the correct EEPROM memory is accessed
when using multiple memory modules on a single I
DIGITAL INPUT/OUTPUT CONFIGURATION
All digital inputs are ESD protected. Digital inputs are high
impedance and can be driven directly from most digital sources.
The RESET digital input pin does not have an internal pull-up
resistor. Therefore, the user should place a pull-up resistor from
RESET to V
internal pull-down resistor. If not driven by an external source,
the AD5255 defaults to a write-protected state. ESD protection
of the digital inputs is shown in Figure 27.
MULTIPLE DEVICES ON ONE BUS
Figure 28 shows four AD5255 devices on the same serial bus.
Each has a different slave address since the state of their AD0
pin and AD1 pin are different. This allows independent reading
and writing to each RDAC within each device.
2
C bus, the AD5255 features two external addressing pins,
MASTER
AD1
AD0
Figure 28. Multiple AD5255 Devices on a Single Bus
SDA
DD
if the function is not used. The WP pin has an
WP
SCL
Figure 27. Equivalent WP ESD Protection
R
P
V
INPUTS
DD
R
P
AD1
AD0
SDA
GND
5V
SCL
V
DD
AD1
AD0
SDA
V
DD
SCL
V
DD
AD1
AD0
SDA
2
C bus.
2
SCL
C data-
SDA
SCL
Rev. A | Page 16 of 20
LEVEL SHIFT FOR BIDIRECTIONAL
COMMUNICATION
While most legacy systems operate at one voltage, adding a new
component might require a different voltage. When two sys-
tems transmit the same signal at two different voltages, use a
level shifter to allow the systems to communicate.
For example, a 3.3 V microcontroller (MCU) can be used along
with a 5 V digital potentiometer. A level shifter is required to
enable bidirectional communication.
Figure 29 shows one of many possible techniques to properly
level-shift signals between two devices. M1 and M2 are
N-channel FETs (2N7002). If V
threshold N-channel FETs (FDV301N) for M1 and M2.
TERMINAL VOLTAGE OPERATION RANGE
The AD5255 positive V
define the boundary conditions for proper 2-terminal program-
mable resistance operation. Supply signals on terminals W and
B that exceed V
biased diodes of the AD5255.
The ground pin of the AD5255 is used as a digital ground
reference and needs to be tied to the common ground of the
PCB. Reference the digital input control signals to the AD5255
ground pin and satisfy the logic levels defined in the Digital
Inputs and Outputs parameters in Table 1.
SDA1
SCL1
V
DD1
Figure 29. Level Shifting for Different Voltage Devices on an I
= 3.3V
Figure 30. Maximum Terminal Voltages Set by V
MCU
3.3V
DD
R
P
or V
SS
DD
R
S
are clamped by the internal forward-
P
and negative V
G
M1
D
DD
S
falls below 2.5 V, use low
G
M2
R
D
P
V
A
W
B
V
SS
DD
SS
power supply inputs
R
AD5255
P
DD
5V
and V
V
2
SS
DD2
C Bus
SDA2
SCL2
= 5V