WMS7201
1. GENERAL DESCRIPTION
The WMS7201 is a 256-tap, single-channel non-volatile digital potentiometer available in 10KΩ, 50KΩ
and 100KΩ end-to-end resistances. These devices can be used as a three-terminal potentiometer or
as a two terminal variable resistor in a wide variety of applications.
The output of the potentiometer is determined by the wiper position, which varies linearly between VA
and VB terminal according to the content stored in the volatile Tap Register (TR). The settings of the
TR can be provided either directly by the user through the industry standard SPI interface, or by the
non-volatile memory (NVMEM0~3) where the previous settings are stored. When changes are made
to the TR to establish a new wiper position, the value of the setting can be saved into any non-volatile
memory location (NVMEM0~3) by executing a NVMEM save operation. Upon powerup the content of
the NVMEM0 is automatically loaded to the Tap Register.
The WMS7201 contains a single potentiometer in 8-pin PDIP, SOIC, MSOP or 10 pin TSSOP
packages and can operate over a wide operating voltage range from 2.7V to 5.5V. A selectable output
buffer is built-in for those applications where an output buffer is required.
2. FEATURES
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256 taps for the potentiometer
End-to-end resistance available in 10KΩ, 50KΩ and 100KΩ
Selectable output buffer for each channel
SPI Serial Interface for data transfer and potentiometer control
Daisy-chain operation for multiple devices (10-pin TSSOP package only)
Nonvolatile storage of four wiper positions per channel with power-on recall from NVMEM0
Low standby current (1µA Max. with output buffer inactive)
Endurance 100K typical stores per bit
Register Data Retention 100 years
Industrial temperature range: -40 ~ 85°C
Wide operating voltage range: 2.7V ~ 5.5V
Package option:
8-pin MSOP, 8-pin SOIC, 8-pin PDIP, 10-pin TSSOP
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WMS7201
4. TABLE OF CONTENTS
1. GENERAL DESCRIPTION.................................................................................................................. 2
2. FEATURES ......................................................................................................................................... 2
3. BLOCK DIAGRAM .............................................................................................................................. 3
4. TABLE OF CONTENTS ...................................................................................................................... 4
5. PIN CONFIGURATION ....................................................................................................................... 5
6. PIN DESCRIPTION ............................................................................................................................. 5
7. FUNCTIONAL DESCRIPTION............................................................................................................ 7
7.1. Potentiometer and Rheostat Modes ............................................................................................. 7
7.1.1. Rheostat Configuration .......................................................................................................... 7
7.1.2. Potentiometer Configuration .................................................................................................. 7
7.2. Programming Modes .................................................................................................................... 7
7.3. Non-Volatile Memory (NVMEM) ................................................................................................... 8
7.3.1 Write Protect of NVMEM ......................................................................................................... 8
7.4 Flow Control................................................................................................................................... 8
7.5. Daisy Chain .................................................................................................................................. 9
7.6. Serial Data Iterface ..................................................................................................................... 10
7.7. Instruction Set............................................................................................................................. 12
7.8. Basic Operation .......................................................................................................................... 12
7.8.1 Sending a Command ............................................................................................................ 12
7.8.2 Wake Up/Sleep/Power Commands ...................................................................................... 13
7.8.3 Write to Tap Register (TR).................................................................................................... 13
7.8.4 Programming Non-Volatile Memory (NVMEM)..................................................................... 14
7.8.5 Reading Tap Register and NVMEM Location (10-pin TSSOP package only)...................... 15
8. TIMING DIAGRAMS.......................................................................................................................... 16
9. ABSOLUTE MAXIMUM RATINGS.................................................................................................... 18
10. ELECTRICAL CHARACTERISTICS ............................................................................................... 19
10.1 Test Circuits............................................................................................................................... 21
11. TYPICAL APPLICATION CIRCUIT ................................................................................................. 22
11.1. Layout Considerations .............................................................................................................. 24
12. PACKAGE DRAWINGS AND DEMINSIONS.................................................................................. 25
13. ORDERING INFORMATION........................................................................................................... 28
14. VERSION HISTORY ....................................................................................................................... 29
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