DS1809

101999

2 of 8

The DS1809 is available in standard 10 k

Ω , 50 kΩ, and 100 kΩ resistor versions. The DS1809 is

provided as an industrial temperature grade part only. Available packaging for the DS1809 include an 8-

lead (300-mil) DIP an 8-lead (150-mil) SOIC, and an 8-lead (118-mil)

µSOP.

BLOCK DIAGRAM Figure 1

OPERATION

The DS1809 Dallastat is a digitally controlled, nonvolatile potentiometer. A block diagram of the

DS1809 is shown in Figure 1. The DS1809 is a linear potentiometer providing 64-uniform wiper

positions over the entire resistor range including the end-terminals. All three potentiometer terminals of

potentiometer. These terminals will have a constant resistance between them as defined by the

potentiometer value chosen: 10 k

Ω, 50 kΩ, or the 100 kΩ version. Functionally, R

DC control inputs, when active, determine the direction on the resistor array that the wiper position will

The control inputs UC and DC are active low inputs which interpret input pulse widths as the means of

Ω resistance. A

transition from a high-to-low on these inputs is considered the beginning of pulse input activity.

A single pulse on the UC or DC input is defined as being greater than 1 millisecond but lasting no longer

that ½ second. This type pulse input will cause the wiper position of the Dallastat to move one position.

Multiple pulse inputs (repetitive pulse inputs) can be used to step through each wiper position of the

device. The requirement for a repetitive pulse train on the UC or DC inputs is that pulses must be

separated by a minimum high time of 1 millisecond. If this is not the case the Dallastat will ignore that

pulse input.