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What is digital potentiometer? Digital potentiometers are variable resistors that can adjust freely setting values by external digital signals. Further, these have the same functions as mechanical potentiometers by writing setting values stored when nonvolatile EEPROM memory is written and electricity is ON. Especially, the latest product series achieve low power consumption and operation currents realize 1mA and standby currents 1 ^A. Standard features are the following: • Without moving parts, environmental characteristics have been improved. • Remote control of the product is possible by digital signals. • Without moving parts, there are absolutely no hysteresis. • Automatic adjustment makes it possible to reduce numbers of adjustment processes. • Space-conscious packages available. On the contrary, there are some disadvantages in digital potentiometers. Different from mechanical potentiometers, the wiper of the digital potentiometers operates like steps. The numbers of the type of total resistance values are few. Temperature characteristics are inferior. Because of its structure of CMOS circuitry used for a wiper changeover switch, frequency characteristics are also inferior to mechanical potentiometers. Other disadvantages include weakness for over-voltage and over-current. Digital potentiometers are categorized by control types and their features as below. • Up/down interface type ___ • 3 control signals control wiper position (U/D, INC, CS) • For wiper positions (number of taps), 32 and 100 types are available. • 2-wire interface type • Uses 2-wire serial interface • Resistor system permits direct reading of wiper position and setting. • Multiple circuits are built into one chip (2-circuit or 4-circuit). • Wiper position of 64 or 128 and 256 taps per circuit • SPI interface type • Resistor system permits direct reading of wiper position and setting. • Multiple circuits are built into one chip (2-circuit or 4-circuit). • Wiper position of 64 or 256 taps per circuit • It operates at 3 Mbps faster than 2-wire interface type • 3-wire interface type • 3-wire of CLK, Dl, and CS controls by ser

• Nominal resistance value Nominal resistance value is the value between terminal Vh and Vl of potentiometers. It depends on each series and in digital potentiometers, it ranges from 1 kQ to 100 kQ. • Maximum input voltage Maximum input voltage is the maximum voltage that can impress between terminals, Vh and Vl. It can impress up to Vcc voltage. • Maximum wiper current This is the maximum current sent to wiper. One of the specifications to be noted in the digital potentiometer is that current is from ± 0.6 mA to ± 6 mA. • Number of taps (Resolution) Resolution in cermet trimmer is...

• Resistance temperature characteristics Resistance temperature characteristics mean changing ratios of total resistance when environmental temperatures change. Resistance temperature coefficient is a unit of one millionth per 1 °C (10'6/°C) (ppm/°C) Resistance temperature (io-6/°C) = R - Ro x1X106 characteristics Ro t - to R : Actual resistance measurement value (Q) at t °C Ro: Actual resistance measurement value (Q) at to °C t : Actual measurement value (°C) of test temperature to: Actual measurement value (°C) of standard temperature Resistance temperature characteristics are...

• Wiper resistance MOS FET channel resistance is linearly placed in wiper terminal to change wiper taps. This figure differs from 50 to 1 kQ depending on types and increases with temperature. • Wiper noise Basically, wiper noise will not be generated as much as when writing in memories. Since Make-Before-Break operation is used and change-over noise is depressed, Total resistance value will be temporarily going down. This means that new wiper tap is made before breaking. • Wiper current leakage While digital potentiometer is in operation, 100 nA typ current leakage will be generated from...

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DIGITAL POTENTIOMETERS ＜ Basic configurations of electronic potentiometers ＞ Programmable Voltage Regulator 555 IC Oscillator 100 k Programmable Instrumentation Amplifier

Legend Pot : No. of poteniometer Tap : No. of taps I/F : Interface type U/D : UP/DOWN SPI : Serial Peripheral Interface 2W : 2-wire interface * Resistance value will vary depending on the package. For details, please contact us. Copal DP

■ FEATURES • 32-position, linear-curved potentiometer • Nonvolatile memory wiper storage • Low-power CMOS technology • Single-power operation: 2.5 V~6.0V • Increment up/down serial interface • Total resistance: 10 kQ, 50 kQ, 100 kQ • SOIC, TSSOP, MSOP and TDFN packages ■ APPLICATIONS • Auto calibration • Remote control adjustment • Offset, gain and zero controls • Rewritable calibration • Contrast, brightness and volume controls • Motor-controlled, feedback system • Programmable analog fun

■ SUMMARY The DP7114 is a programmable digital potentiometer designed to replace mechanical potentiometers and variable resistors. Automated adjustment by product automation line is ideal. The DP7114 makes this possible and is suitable for applications where it is difficult to operate when machines require constant adjustment or in case of danger or at remote locations. The DP7114 has a 32-tap resistance array between two terminals, RH and RL. The up/down counter and decoder controlled by 3 input terminals determines the tap connected to wiper resistance RW. Wiper settings stored in...