AD5173BRM2.5-RL7 Analog Devices Inc, AD5173BRM2.5-RL7 Datasheet - Page 16

• Manufacturer Part Number: AD5173BRM2.5-RL7
• Description: IC DGTL POT DUAL 2.5K OTP 10MSOP
• Manufacturer: Analog Devices Inc

Specifications of AD5173BRM2.5-RL7

• Rohs Status: RoHS non-compliant
• Taps: 256
• Resistance (ohms): 2.5K
• Number Of Circuits: 2
• Temperature Coefficient: 35 ppm/°C Typical
• Memory Type: Non-Volatile
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Resistance In Ohms: 2.5K
• Number Of Elements: 2
• # Of Taps: 256
• Resistance (max): 2.5KOhm
• Power Supply Requirement: Single
• Interface Type: Serial (2-Wire/I2C)
• Single Supply Voltage (typ): 3/5V
• Dual Supply Voltage (typ): Not RequiredV
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Pin Count: 10
• Lead Free Status / RoHS Status: Not Compliant

AD5172/AD5173
The general equation that determines the digitally programmed
output resistance between W and B is
where:
D is the decimal equivalent of the binary code loaded in the
8-bit RDAC register.
R
R
the internal switch.
In summary, if R
the output resistance, R
codes, as listed in Table 8.
Table 8. Codes and Corresponding R
D (Dec)
255
128
1
0
Note that in the zero-scale condition, a finite wiper resistance of
100 Ω is present. Care should be taken to limit the current flow
between W and B in this state to a maximum pulse current of
no more than 20 mA. Otherwise, degradation or possible destruc-
tion of the internal switch contact may occur.
Similar to the mechanical potentiometer, the resistance of the
RDAC between Wiper W and Terminal A also produces a digi-
tally controlled complementary resistance, R
terminals are used, the B terminal can be opened. Setting the
resistance value for R
and decreases as the data loaded in the latch increases in value.
The general equation for this operation is
AB
W
is the wiper resistance contributed by the on resistance of
is the end-to-end resistance.
R
R
WB
WA
(
(
Figure 41. AD5172/AD5173 Equivalent RDAC Circuit
D
D
R
9961
5060
139
100
)
)
=
WB
=
128
D7
D6
D5
D4
D3
D2
D1
D0
DECODER
AB
256
(Ω)
D
LATCH
RDAC
128
AND
is 10 kΩ and the A terminal is open circuited,
×
–
WA
R
D
AB
Output State
Full scale (R
Midscale
1 LSB
Zero scale (wiper contact resistance)
WB
starts at a maximum value of resistance
×
, is set according to the RDAC latch
R
+
AB
2
R
R
R
R
×
S
S
S
S
+
R
2
W
×
AB
R
W
– 1 LSB + R
WB
Resistance
WA
A
W
B
. When these
W
)
Rev. H | Page 16 of 24
(1)
(2)
When R
output resistance, R
codes, as listed in Table 9.
Table 9. Codes and Corresponding R
D (Dec)
255
128
1
0
Typical device-to-device matching is process-lot dependent
and can vary up to ±30%. Because the resistance element is
processed using thin-film technology, the change in R
temperature has a very low temperature coefficient of 35 ppm/°C.
PROGRAMMING THE POTENTIOMETER DIVIDER
Voltage Output Operation
The digital potentiometer easily generates a voltage divider at
wiper to B and at wiper to A, proportional to the input voltage
at A to B. Unlike the polarity of V
positive, voltage across A to B, W to A, and W to B can be at
either polarity.
If ignoring the effect of the wiper resistance for approximation,
connecting the A terminal to 5 V and the B terminal to ground
produces an output voltage at the wiper to B, starting at 0 V up
to 1 LSB less than 5 V. Each LSB of voltage is equal to the vol-
tage applied across Terminal A and Terminal B divided by the
256 positions of the potentiometer divider. The general equation
defining the output voltage at V
valid input voltage applied to Terminal A and Terminal B is
A more accurate calculation, which includes the effect of wiper
resistance, V
Operation of the digital potentiometer in the divider mode
results in more accurate operation over temperature. Unlike in
the rheostat mode, the output voltage is dependent mainly on
the ratio of the internal resistors, R
values. Therefore, the temperature drift reduces to 15 ppm/°C.
V
V
W
W
AB
(
(
D
D
is 10 kΩ and the B terminal is open circuited, the
)
)
=
=
W
Figure 42. Potentiometer Mode Configuration
, is
256
R
D
WB
R
R
139
5060
9961
10,060
AB
V
(
WA
WA
D
A
)
V
, is set according to the RDAC latch
+
(Ω)
V
I
256
A
256
+
−
R
A
B
WA
D
R
W
AB
W
V
(
WA
D
DD
with respect to ground for any
B
)
and R
Output State
Full scale
Midscale
1 LSB
Zero scale
to GND, which must be
V
V
B
WA
O
WB
Resistance
, not on the absolute
AB
with
(3)
(4)