Datasheet > AD5245BRJ5-R2

AD5245BRJ5-R2

更新时间： 2024-01-28 17:53:36

品牌	Logo	应用领域
亚德诺 - ADI		数字电位计
页数	文件大小	规格书
16页	853K
描述
256-Position I2C Compatible Digital Potentiometer

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数据手册
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AD5245BRJ5-R2 数据手册

AD5245

OPERATION

The AD5245 is a 256-position digitally controlled variable

resistor (VR) device.

The general equation determining the digitally programmed

output resistance between W and B is

An internal power-on preset places the wiper at midscale

during power-on, which simplifies the fault condition recovery

at power-up.

256

R_WB(D) =

×R_AB+R_W

(1)

where D is the decimal equivalent of the binary code loaded in

the 8-bit RDAC register, R_ABis the end-to-end resistance, and

R_Wis the wiper resistance contributed by the on resistance of

the internal switch.

PROGRAMMING THE VARIABLE RESISTOR

Rheostat Operation

The nominal resistance of the RDAC between terminals A and

B is available in 5 kΩ, 10 kΩ, 50 kΩ, and 100 kΩ. The final two

or three digits of the part number determine the nominal

resistance value, e.g., 10 kΩ = 10ꢀ 50 kΩ = 50. The nominal

resistance (R_AB) of the VR has 256 contact points accessed by

the wiper terminal, plus the B terminal contact. The 8-bit data

in the RDAC latch is decoded to select one of the 256 possible

settings. Assume a 10 kΩ part is used, the wiper’s first

connection starts at the B terminal for data 0x00. Since there is a

60 Ω wiper contact resistance, such connection yields a

minimum of 60 Ω resistance between terminals W and B. The

second connection is the first tap point, which corresponds to

99 Ω (R_WB= R_AB/256 + R_W= 39 Ω + 60 Ω) for data 0x01.

The third connection is the next tap point, representing 177 Ω

(2 × 39 Ω + 60 Ω) for data 0x02, and so on. Each LSB data value

increase moves the wiper up the resistor ladder until the last tap

point is reached at 9961 Ω (R_AB– 1 LSB + R_W). Figure 39 shows

a simplified diagram of the equivalent RDAC circuit where the

last resistor string will not be accessedꢀ therefore, there is 1 LSB

less of the nominal resistance at full scale in addition to the

wiper resistance.

In summary, if R_AB= 10 kΩ and the A terminal is open

circuited, the following output resistance R_WBwill be set for the

indicated RDAC latch codes.

Table 7. Codes and Corresponding R_WBResistance

D (Dec.)

R_WB(Ω)

9,961

5,060

Output State

255

128

Full Scale (R_AB– 1 LSB + R_W)

Midscale

1 LSB

Zero Scale (Wiper Contact Resistance)

Note that in the zero-scale condition a finite wiper resistance of

60 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

destruction of the internal switch contact can occur.

Similar to the mechanical potentiometer, the resistance of the

RDAC between the wiper W and terminal A also produces a

digitally controlled complementary resistance R_WA. When these

terminals are used, the B terminal can be opened. Setting the

resistance value for R_WAstarts at a maximum value of resistance

and decreases as the data loaded in the latch increases in value.

The general equation for this operation is

SD BIT

R_S

256 − D

256

R_WA(D) =

×R_AB+ R_W

(2)

R_S

For R_AB= 10 kΩ and the B terminal open circuited, the

following output resistance R_WAwill be set for the indicated

RDAC latch codes.

RDAC

Table 8. Codes and Corresponding R_WAResistance

LATCH

R_S

DECODER

AND

D (Dec.)

R_WA(Ω)

Output State

Full Scale

Midscale

1 LSB

255

128

5,060

9,961

10,060

Figure 39. AD5245 Equivalent RDAC Circuit

Zero Scale

Typical device to device matching is process lot dependent and

may vary by up to 30%. Since the resistance element is

processed in thin film technology, the change in R_ABwith

temperature has a very low 45 ppm/°C temperature coefficient.

Rev. 0 | Page 12 of 16

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AD5245BRJ5-R2 替代型号

型号	品牌	替代类型	描述	数据表
AD5245BRJZ5-RL7	ADI	完全替代	256-Position I2C-Compatible Digital Potentiometer
AD5245BRJZ5-R2	ADI	完全替代	256-Position I2C-Compatible Digital Potentiometer
AD5245BRJ5-RL7	ADI	完全替代	256-Position I2C Compatible Digital Potentiometer

与AD5245BRJ5-R2相关器件

型号	品牌	获取价格	描述	数据表
AD5245BRJ5-RL7	ADI	获取价格	256-Position I2C Compatible Digital Potentiometer
AD5245BRJZ10	ADI	获取价格	10K DIGITAL POTENTIOMETER, 2-WIRE SERIAL CONTROL INTERFACE, 256 POSITIONS, PDSO8
AD5245BRJZ100-R2	ADI	获取价格	256-Position I2C-Compatible Digital Potentiometer
AD5245BRJZ100-R21	ADI	获取价格	256-Position I2C-Compatible Digital Potentiometer
AD5245BRJZ100-RL7	ADI	获取价格	256-Position I2C-Compatible Digital Potentiometer
AD5245BRJZ100-RL71	ADI	获取价格	256-Position I2C-Compatible Digital Potentiometer
AD5245BRJZ10-R2	ADI	获取价格	256-Position I2C-Compatible Digital Potentiometer
AD5245BRJZ10-R21	ADI	获取价格	256-Position I2C-Compatible Digital Potentiometer
AD5245BRJZ10-RL7	ADI	获取价格	256-Position I2C-Compatible Digital Potentiometer
AD5245BRJZ10-RL71	ADI	获取价格	256-Position I2C-Compatible Digital Potentiometer

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