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PDF ( 数据手册 , 数据表 ) AD5173

零件编号 AD5173
描述 Dual-Channel I2C Digital Potentiometers
制造商 Analog Devices
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AD5173 数据手册, 描述, 功能
Data Sheet
256-Position, One-Time Programmable,
Dual-Channel, I2C Digital Potentiometers
AD5172/AD5173
FEATURES
2-channel, 256-position potentiometers
One-time programmable (OTP) set-and-forget resistance
setting provides a low cost alternative to EEMEM
Unlimited adjustments prior to OTP activation
OTP overwrite allows dynamic adjustments with user-
defined preset
End-to-end resistance: 2.5 kΩ, 10 kΩ, 50 kΩ, and 100 kΩ
Compact 10-lead MSOP: 3 mm × 4.9 mm
Fast settling time: tS = 5 μs typical on power-up
Full read/write of wiper register
Power-on preset to midscale
Extra package address decode pins: AD0 and AD1 (AD5173 )
Single supply: 2.7 V to 5.5 V
Low temperature coefficient: 35 ppm/°C
Low power: IDD = 6 μA maximum
Wide operating temperature: −40°C to +125°C
FUNCTIONAL BLOCK DIAGRAMS
A1 W1 B1
A2 W2 B2
VDD
GND
FUSE
LINKS
12
RDAC
REGISTER 1
RDAC
REGISTER 2
SDA
SCL
/8
SERIAL INPUT
REGISTER
Figure 1. AD5172 Functional Block Diagram
W1 B1
W2 B2
APPLICATIONS
Systems calibration
Electronics level setting
Mechanical trimmers replacement in new designs
Permanent factory PCB setting
Transducer adjustment of pressure, temperature, position,
chemical, and optical sensors
RF amplifier biasing
Automotive electronics adjustment
Gain control and offset adjustment
GENERAL DESCRIPTION
The AD5172/AD5173 are dual-channel, 256-position, one-time
programmable (OTP) digital potentiometers1 that employ fuse
link technology to achieve memory retention of resistance
settings. OTP is a cost-effective alternative to EEMEM for users
who do not need to program the digital potentiometer setting
in memory more than once. These devices perform the same
electronic adjustment function as mechanical potentiometers or
variable resistors but with enhanced resolution, solid-state reliabil-
ity, and superior low temperature coefficient performance.
The AD5172/AD5173 are programmed using a 2-wire, I2C®-
compatible digital interface. Unlimited adjustments are allowed
VDD
GND
FUSE
LINKS
12
RDAC
REGISTER 1
RDAC
REGISTER 2
AD0 ADDRESS
/AD1
DECODE
8
SDA
SCL
SERIAL INPUT
REGISTER
Figure 2. AD5173 Functional Block Diagram
before permanently setting the resistance value. During OTP
activation, a permanent blow fuse command freezes the wiper
position (analogous to placing epoxy on a mechanical trimmer).
Unlike traditional OTP digital potentiometers, the AD5172/
AD5173 have a unique temporary OTP overwrite feature that
allows for new adjustments even after a fuse is blown. However,
the OTP setting is restored during subsequent power-up condi-
tions. This allows users to treat these digital potentiometers as
volatile potentiometers with a programmable preset.
1 The terms digital potentiometer, VR, and RDAC are used interchangeably.
Rev. I
Document Feedback
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any 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 or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2003–2013 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com







AD5173 pdf, 数据表
AD5172/AD5173
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.
Table 4.
Parameter
VDD to GND
VA, VB, VW to GND
Terminal Current, Ax to Bx, Ax to Wx, Bx to Wx1
Pulsed
Continuous
Digital Inputs and Output Voltage to GND
Operating Temperature Range
Maximum Junction Temperature (TJMAX)
Storage Temperature Range
Reflow Soldering
Peak Temperature
Time at Peak Temperature
Thermal Resistance2
θJA for 10-Lead MSOP
Rating
−0.3 V to +7 V
−0.3 V to +7 V or
VDD + 0.3 V
(whichever is less)
±20 mA
±5 mA
−0.3 V to +7 V or
VDD + 0.3 V
(whichever is less)
−40°C to +125°C
150°C
−65°C to +150°C
260°C
20 sec to 40 sec
200°C/W
1 The maximum terminal current is bound by the maximum current handling
of the switches, the maximum power dissipation of the package, and the
maximum applied voltage across any two of the A, B, and W terminals at a
given resistance.
2 The package power dissipation is (TJMAX − TA)/θJA.
Data Sheet
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
Rev. I | Page 8 of 28







AD5173 equivalent, schematic
AD5172/AD5173
THEORY OF OPERATION
SCL
SDA
I2C INTERFACE
DAC
REG
MUX
DECODER
COMPARATOR
ONE-TIME
PROGRAM/TEST
CONTROL BLOCK
FUSES
EN
FUSE
REG
Data Sheet
A
W
B
Figure 39. Detailed Functional Block Diagram
The AD5172/AD5173 are 256-position, digitally controlled
variable resistors (VRs) that employ fuse link technology to
achieve memory retention of the resistance setting.
An internal power-on preset places the wiper at midscale
during power-on. If the OTP function is activated, the device
powers up at the user-defined permanent setting.
ONE-TIME PROGRAMMING (OTP)
Prior to OTP activation, the AD5172/AD5173 presets to midscale
during initial power-on. After the wiper is set to the desired
position, the resistance can be permanently set by programming
the T bit high, with the proper coding (see Table 8 and Table 9),
and one-time VDD_OTP. The fuse link technology of the AD517x
family of digital potentiometers requires VDD_OTP to be between
5.6 V and 5.8 V to blow the fuses to achieve a given nonvolatile
setting. However, during operation, VDD can be 2.7 V to 5.5 V. As a
result, an external supply is required for one-time programming.
The user is allowed only one attempt to blow the fuses. If the user
fails to blow the fuses during this attempt, the structure of the
fuses can change such that they may never be blown, regardless
of the energy applied during subsequent events. For details, see
the Power Supply Considerations section.
The device control circuit has two validation bits, E1 and E0,
that can be read back to check the programming status (see
Table 7). Users should always read back the validation bits to
ensure that the fuses are properly blown. After the fuses are
blown, all fuse latches are enabled upon subsequent power-on;
therefore, the output corresponds to the stored setting. Figure 39
shows a detailed functional block diagram.
Table 7. Validation Status
E1 E0 Status
0 0 Ready for programming.
10
Fatal error. Some fuses are not blown. Do not retry.
Discard this unit.
1 1 Successful. No further programming is possible.
PROGRAMMING THE VARIABLE RESISTOR AND
VOLTAGE
Rheostat Operation
The nominal resistance of the RDAC between Terminal A and
Terminal B is available in 2.5 kΩ, 10 kΩ, 50 kΩ, and 100 kΩ.
The nominal resistance (RAB) of the VR has 256 contact points
accessed by the wiper terminal and the B terminal contact. The
8-bit data in the RDAC latch is decoded to select one of the
256 possible settings.
A
W
A
W
A
W
BB
B
Figure 40. Rheostat Mode Configuration
Assuming a 10 kΩ part is used, the first connection of the wiper
starts at the B terminal for Data 0x00. Because there is a 50 Ω
wiper contact resistance, such a connection yields a minimum
of 100 Ω (2 × 50 Ω) resistance between Terminal W and Ter-
minal B. The second connection is the first tap point, which
corresponds to 139 Ω (RWB = RAB/256 + 2 × RW = 39 Ω + 2 ×
50 Ω) for Data 0x01. The third connection is the next tap point,
representing 178 Ω (2 × 39 Ω + 2 × 50 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 10,100 Ω (RAB + 2 × RW).
Rev. I | Page 16 of 28










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