X9428_06 Datasheet, PDF(7/21 Page) Intersil Corporation – Single Digitally Controlled Potentiometer

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X9428_06 Datasheet, PDF (7/21 Pages) Intersil Corporation – Single Digitally Controlled Potentiometer

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Figure 3. Two-Byte Instruction Sequence

X9428

SCL

SDA

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

The Increment/Decrement command is different from

the other commands. Once the command is issued

and the X9428 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/RH

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

Read Wiper Counter

I3 I2 I1 I0 R1 R0 X1 X0

Operation

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

Write Wiper Counter

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

Read Data Register

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

R1 - R0

Write Data Register

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

R1 - R0

XFR Data Register to

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

Wiper Counter Register

by R1 - R0 to its Wiper Counter Register

XFR Wiper Counter

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

to the Data Register pointed to by R1 - R0

Increment/Decrement

0 0 1 0 0 0 0 1/0 Enable Increment/decrement of the Wiper Counter

Wiper Counter Register

Note: (7) 1/0 = data is one or zero

FN8197.1

April 26, 2006

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