Variable resistor

Dallas Semiconductor has released the DS3906, a triple variable resistor for low resistance, small step-size applications.

This device's three 64-step, digital, non-volatile variable resistors are capable of ohm and sub-ohm step sizes when used in parallel with a fixed external resistor.

All three resistors have 64 positions (plus a high-Z state) with a pseudo-log response chosen to have a linear equivalent resistance when paired with an external resistor.

Two of the variable resistors have a range of 66 to 101 ohm with about 0.5 ohm step sizes (when used with a 105 ohm external resistor), while the third variable resistor has a range of 187 to 255 ohm with about 1 ohm step sizes (when used with a 310 ohm external resistor).

The device is suitable for applications requiring calibration. Unlike mechanical potentiometers, this device enables manufacturers to optimise production by automating calibration while also improving the quality and reliability of their product.

The device contains 16 bytes of user EEPROM that, like the resistors, are controlled through an I2C-compatible serial interface. Three address pins allow up to eight DS3906s to be placed on this same I2C bus.