DS1809 Dallastat FEATURES PIN ASSIGNMENT 64-Position Linear Taper Two Nonvolatile Wiper Storage Options R 1 8 V H CC Operates from +4.5V to +5.5V Supplies UC 2 7 DC Operating Temperature Range: - Industrial: -40C to +85C STR 3 6 R W Electronic Interface Provides Either Digital R 4 5 GND or Pushbutton Control L Low-Cost Alternative to Mechanical Solutions PDIP (300 mils) Standard Resistance Values SO (150 mils) - DS1809-010 10k SOP (118 mils) - DS1809-050 50k PIN DESCRIPTION - DS1809-100 100k V - Supply Voltage CC R - High End of Resistor H R - Low End of Resistor L R - Wiper Terminal W UC - Up Control Input DC - Down Control Input STR - Storage Enable Input GND - Ground DESCRIPTION The DS1809 Dallastat is a nonvolatile digitally controlled potentiometer that provides 64 uniform wiper positions over the entire resistor range including the high-end and low-end terminals of the device. The DS1809 is a low-power device capable of operating from power supplies of +4.5V to +5.5V. The device is ideal for low-power, portable, or battery powered applications. Wiper position is maintained in the absence of power. This is accomplished via the use of an EEPROM cell array. The device provides for two storage methods, which include an autostore capability and a command-initiated storage function. The EEPROM cell array is specified to accept greater than 50k writes. Storage of the wiper position is discussed in the Wiper Storage section of this data sheet. Wiper positioning is controlled via a dual pushbutton (or contact closure) interface. For simple pushbutton-controlled applications or CPU-generated control signals, external debounce circuitry is not needed. The control interface will support both repetitive pulse inputs and continuous pulse (push-and- hold) inputs. Repetitive pulse and continuous pulse control as well as timing diagrams are discussed in the Operation. The DS1809 is available in standard 10 k, 50 k, and 100 k resistor versions. The DS1809 is provided as an industrial temperature grade part only. Available packaging for the DS1809 include an 8- lead (300-mil) PDIP, an 8-lead (150-mil) SO, and an 8-lead (118-mil) SOP. 1 of 10 19-7387 Rev 4/14 DS1809 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 the device are accessible. These terminals include R , R , and R . R and R are the end-terminals of the H L W H L potentiometer. These terminals will have a constant resistance between them as defined by the potentiometer value chosen: 10k, 50k, or the 100k version. Functionally, R and R are H L interchangeable. The wiper terminal, R , is the multiplexed terminal and can be set to one of the 64 total W positions that exist on the resistor ladder including the R and R terminals. H L Control of the wiper (R ) position setting is accomplished via the two inputs UC and DC. The UC and W DC control inputs, when active, determine the direction on the resistor array that the wiper position will move. The UC (up control) control input is used to move the wiper position towards the R terminal. The H DC (down control) control input is used to move wiper position towards the R terminal. L The control inputs UC and DC are active low inputs that interpret input pulse widths as the means of controlling wiper movement. Internally, these inputs are pulled up to V via a 100k resistance. A CC 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 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 1ms. If this is not the case the Dallastat will ignore that pulse input. A continuous pulse input (push and hold) is defined as lasting longer that one-half second. A continuous pulse input will cause the wiper position to move one position every 100 milliseconds following the initial one-half-second hold time. The total time to transcend the entire potentiometer given a continuous pulse input is provided by the equation: 2 of 10