X9258 Datasheet, PDF(5/20 Page) Xicor Inc. – Quad Digital Controlled Potentiometers (XDCP)

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X9258 Datasheet, PDF (5/20 Pages) Xicor Inc. – Quad Digital Controlled Potentiometers (XDCP)

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Figure 3. Two-Byte Instruction Sequence

SCL

X9258

SDA

S 0 1 0 1 A3 A2 A1 A0 A I3 I2 I1 I0 R1 R0 P1 P0 A S

The Increment/Decrement command is different from

the other commands. Once the command is issued

and the X9258 has responded with an acknowledge,

the master can clock the selected wiper up and/or

down in one segment steps; thereby, providing a fine

tuning capability to the host. For each SCL clock pulse

(tHIGH) while SDA is HIGH, the selected wiper will

move one resistor segment towards the VH terminal.

Similarly, for each SCL clock pulse while SDA is LOW,

the selected wiper will move one resistor segment

towards the VL/RL terminal. A detailed illustration of

the sequence and timing for this operation are shown

in Figures 5 and 6 respectively.

Table 1. Instruction Set

Instruction Set

Instruction

I3 I2 I1 I0 R1 R0 P1 P0

Operation

Read Wiper Counter

1 0 0 1 0 0 1/0 1/0 Read the contents of the Wiper Counter Register

pointed to by P1 - P0

Write Wiper Counter

1 0 1 0 0 0 1/0 1/0 Write new value to the Wiper Counter Register

pointed to by P1 - P0

Read Data Register

1 0 1 1 1/0 1/0 1/0 1/0 Read the contents of the Data Register pointed

to by P1 - P0 and R1 - R0

Write Data Register

1 1 0 0 1/0 1/0 1/0 1/0 Write new value to the Data Register pointed to

by P1 - P0 and R1 - R0

XFR Data Register to

1 1 0 1 1/0 1/0 1/0 1/0 Transfer the contents of the Data Register pointed

Wiper Counter Register

to by P1 - P0 and R1 - R0 to its associated Wiper

Counter Register

XFR Wiper Counter

Global XFR Data

Registers to Wiper

Counter Registers

1 1 1 0 1/0 1/0 1/0 1/0 Transfer the contents of the Wiper Counter Reg-

ister pointed to by P1 - P0 to the Data Register

pointed to by R1 - R0

0 0 0 1 1/0 1/0 0

0 Transfer the contents of the Data Registers

pointed to by R1 - R0 of all four pots to their re-

spective Wiper Counter Registers

Global XFR Wiper

Counter Registers

to Data Register

1 0 0 0 1/0 1/0 0

0 Transfer the contents of both Wiper Counter

Registers to their respective data Registers

pointed to by R1 - R0 of all four pots

Increment/Decrement

0 0 1 0 0 0 1/0 1/0 Enable Increment/decrement of the Control Latch

Wiper Counter Register

pointed to by P1 - P0

Note: (1) 1/0 = data is one or zero

FN8168.1

May 6, 2005

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