Dual, 256-Tap, Nonvolatile, SPI-Interface,

Linear-Taper Digital Potentiometers

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9

Write-Wiper Register (Command 00)

Data written to the write-wiper registers (C1, C0 = 00)

controls the wiper positions. The 8 data bits (D7 to D0)

indicate the position of the wiper. For example, if DIN =

0000 0000, the wiper moves to the position closest to

L_. If DIN = 1111 1111, the wiper moves closest to H_.

This command writes data to the volatile RAM, leaving the

NV registers unchanged. When the device powers up,

the data stored in the NV registers transfers to the volatile

wiper register, moving the wiper to the stored position.

Write-NV Register (Command 01)

This command (C1, C0 = 01) stores the position of the

wipers to the NV registers for use at power-up.

Alternatively, the “copy wiper register to NV register”

command can be used to store the position of the

wipers to the NV registers. Writing to the NV registers

does not affect the position of the wipers.

Copy Wiper Register to NV Register (Command 10)

This command (C1, C0 = 10) stores the current position

of the wiper to the NV register, for use at power-up.

This command may affect one potentiometer at a time,

Table 1. Register Map

123456789

10

11

12

13

14

15

16

CLOCK EDGE

—

—

C1

C0

—

—

A1

A0

D7

D6

D5

D4

D3

D2

D1

D0

Write Wiper Register A

00000001

D7

D6

D5

D4

D3

D2

D1

D0

Write Wiper Register B

00000010

D7

D6

D5

D4

D3

D2

D1

D0

Write NV Register A

00010001

D7

D6

D5

D4

D3

D2

D1

D0

Write NV Register B

00010010

D7

D6

D5

D4

D3

D2

D1

D0

Copy Wiper Register A to NV

Register A

00100001

————

—

—

—

—

Copy Wiper Register B to NV

Register B

00100010

————

—

—

—

—

Copy Both Wiper Registers to

NV Registers

00100011

————

—

—

—

—

Copy NV Register A to Wiper

Register A

00110001

————

—

—

—

—

Copy NV Register B to Wiper

Register B

00110010

————

—

—

—

—

Copy Both NV Registers to

Wiper Registers

00110011

————

—

—

—

—

Figure 2. Timing Diagram

CS

SCLK

DIN