wms7202 Winbond Electronics Corp America, wms7202 Datasheet - Page 10

• Manufacturer Part Number: wms7202
• Description: 256-tap Dual-channel Non-volatile Digital
• Manufacturer: Winbond Electronics Corp America

The WMS7202 contains a four-wire SPI interface:
The key features of this interface include:
The serial interface uses an SPI compatible uniform 24-bit word format as shown below. This format is
used for all members of the WMS720x family. The data is sent MSB first.
C3-C0 are the command bits that control the operation of the digital potentiometer according to the
command instructions shown in the Instruction Set in Table 5 in Section 7.7.
A1 and A0 are the address bits that determine which channel is activated, as shown in the table
below. For the WMS7202 only the first two codes are used.
MSB
C3
7.6. S
x
x
x
x
x
x
x
x
x
x
C2
SDO (Serial Data Output) Used for reading out the internal register contents and for daisy
chaining multiple devices.
SDI (Serial Data Input) Used for clocking in commands and potentiometer settings.
CS (Chip Select) This pin must be pulled LOW before starting to send a command and pulled
HIGH to signal the end of the command. This pin can be used to control multiple devices on
the bus.
CLK (Clock) The SDI bits are shifted in on the rising edge of the clock and SDO data is
shifted out on the falling edge of the clock.
Independently programmable Read & Write to all registers
Direct parallel refresh of all Tap registers from corresponding internal NVMEM registers
Increment and decrement instruction for each Tap register
Nonvolatile storage of the present Tap register values into one of the four NVMEM registers
available to each channel
Configurable output buffer amplifier to allow both the functions of a potentiometer and a
variable resistor
Four 9-bit non-volatile registers store four preset wiper positions and the first one will be
recalled to set the wiper position during power up.
ERIAL
C1
C0
D
ATA
A3
I
NTERFACE
A2
A1
TABLE 2 – 24-BIT DATA WORD FORMAT
A0
X
X
X
X
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X
X
X
D8
D7
D6
D5
D4
WMS7202
D3
D2
D1
LSB
D0