DS1667

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same. The DS1667 also contains two high gain wide bandwidth operational amplifiers. Each amplifier

has both the inverting and non-inverting inputs and the output available for user configuration. The

operational amplifiers can be paired with the resistive elements to perform such functions as analog to

digital conversion, digital to analog conversion, variable gain amplifiers, and variable oscillators.

OPERATION - DIGITAL RESISTOR SECTION

The DS1667 contains two potentiometers, each of which has its wiper set by a value contained in an 8-bit

register (see Figure 1). Each potentiometer consists of 256 resistors of equal value with tap points

between each resistor and at the low end.

In addition, the potentiometer can be stacked by connecting them in series such that the high end of

potentiometer 0 is connected to the low end of potentiometer 1. When stacking potentiometers, the stack

select bit is used to select which potentiometer wiper will appear at the stack multiplexer output (SOUT).

A zero written to the stack multiplexer will connect wiper 0 to the SOUT pin. This wiper will determine

which of the 256 bottom taps of the stacked potentiometer is selected. When a 1 is written to the stack

multiplexer, wiper 1 is selected and one of the upper 256 taps of the stacked potentiometer is presented at

the SOUT pin.

BLOCK DIAGRAM Figure 1

Information is written to and read from the wiper 0 and wiper 1 registers and the stack select bit via the

DQ, and CLK. It is updated by transferring all 17 bits (Figure 2). Data can be entered into the 17-bit shift

ignored.