257-tap I²C digipot for precision analog trimming
The MCP4552T-503E/MF is a single-channel, 50 kOhm digital potentiometer from Microchip, configured as a rheostat with 257 wiper taps. The I²C interface and volatile memory make it a straightforward drop-in for processor-controlled gain, offset, or bias adjustments in analog signal chains. The 8-DFN (3x3 mm) exposed-pad package pulls heat into the board plane — the pad should be soldered to a copper pour for thermal relief in high-ambient designs.
Taper, tolerance, and temperature drift
Linear taper means the resistance between the wiper and terminal B changes in equal steps across the 257 positions — each step is 50 kOhm / 256 ≈ 195 Ohm. The ±20% absolute tolerance on the end-to-end resistance is typical for digital pots; the ratiometric accuracy between taps is tighter, which is what matters in divider applications. Temperature coefficient is 150 ppm/°C typical. The wiper resistance is 75 ohms typical, adding a small series offset that becomes significant only at the lowest resistance settings.
Bus integration and addressability
The I²C interface runs on the same 1.8V to 5.5V rail as the pot core — no level translator needed if the bus voltage matches. The selectable address feature (tied to an external pin) lets two MCP4552 devices share the same I²C bus without conflict. The mute function forces the wiper to the B terminal position, useful for power-on muting in audio paths or for setting a known start state during calibration.