Dual 30k/50k digital rheostat — 256-tap I²C trimmer
The DS3902U-530+ is a dual-channel digital potentiometer from Analog Devices, configured as a rheostat with 256 taps per channel. One channel is 30 kΩ, the other 50 kΩ — both with linear taper, so the wiper resistance changes linearly with the digital code. The non-volatile memory retains the wiper position after power-off, eliminating the need for a re-initialization routine on each power-up. The I²C interface with selectable address allows up to eight DS3902 devices on the same bus without address conflict, which is handy when multiple calibration points share a two-wire bus.
Industrial temperature range and package fit
Rated for -40°C to +95°C operating ambient, the DS3902U-530+ suits factory-floor or outdoor equipment enclosures where temperature swings are common. The ±20% tolerance on the absolute resistance value means the end-to-end resistance can vary by 20% from lot to lot, but the wiper ratio (256 steps) is accurate. The ±300 ppm/°C temperature coefficient adds about 0.03% drift per °C — acceptable for trimming loops but not for precision references.