Discrete Analog Capsense + CC Driver

// Published on May 12, 2026

Pictures

Analog module integrated into an old design for a desklamp with 32 individually addressable LED filaments, 4096 steps of resolution at 3A max.
4th order Sallen-Key LPF (butterworth) to filter a 100kHz square from the MCU into 100kHz 3.0V VPP sine for capacitive touch sensing.
Discrete op-amp envelope detection + gain stages
Mixed signal discipline practiced; high impedance sensing pads isolated away from PWM LED drivers
0402 passives for space efficiency & robustness

*todo