Datasheet

MAX5487/MAX5488/MAX5489
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
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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
12345678910111213141516
CLOCK EDGE
— — C1 C0 — — A1 A0 D7 D6 D5 D4 D3 D2 D1 D0
Write Wiper Register A 00000001D7D6D5D4D3D2D1D0
Write Wiper Register B 00000010D7D6D5D4D3D2D1D0
Write NV Register A 00010001D7D6D5D4D3D2D1D0
Write NV Register B 00010010D7D6D5D4D3D2D1D0
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
t
CSO
t
CSS
t
CL
t
CH
t
DH
t
DS
t
CP
t
CSH
t
CSW
t
CS1
SCLK
DIN