CAT5419_13 Datasheet, PDF (9/15 Pages) ON Semiconductor – Dual Digital Potentiometer (POT)

ID3
0
(MSB)
Device Type Identifier
ID2
ID1
1
0
CAT5419
ID0
A3
1
Slave Address
A2
A1
Figure 8. Identification Byte Format
A0
(LSB)
I3
(MSB)
Instruction
Opcode
I2
I1
Data Register
Selection
I0
R1
R0
Figure 9. Instruction Byte Format
WCR/Pot Selection
0
P0
(LSB)
WIPER CONTROL AND DATA REGISTERS
Wiper Control Register (WCR)
The CAT5419 contains two 6-bit Wiper Control
Registers, one for each potentiometer. The Wiper Control
Register output is decoded to select one of 64 switches along
its resistor array. The contents of the WCR can be altered in
four ways: it may be written by the host via Write Wiper
Control Register instruction; it may be written by
transferring the contents of one of four associated Data
Registers via the XFR Data Register instruction, it can be
modified one step at a time by the Increment/Decrement
instruction (see Instruction section for more details).
Finally, it is loaded with the content of its data register zero
(DR0) upon power-up.
The Wiper Control Register is a volatile register that loses
its contents when the CAT5419 is powered-down. Although
the register is automatically loaded with the value in DR0
upon power-up, this may be different from the value present
at power-down.
Data Registers (DR)
Each potentiometer has four 6-bit non-volatile Data
Registers. These can be read or written directly by the host.
Data can also be transferred between any of the four Data
Registers and the associated Wiper Control Register. Any
data changes in one of the Data Registers is a non-volatile
operation and will take a maximum of 5 ms.
If the application does not require storage of multiple
settings for the potentiometer, the Data Registers can be used
as standard memory locations for system parameters or user
preference data.
Instructions
Four of the nine instructions are three bytes in length.
These instructions are:
 Read Wiper Control Register – read the current wiper
position of the selected potentiometer in the WCR
 Write Wiper Control Register – change current wiper
position in the WCR of the selected potentiometer
 Read Data Register – read the contents of the selected
Data Register
 Write Data Register – write a new value to the
selected Data Register.
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