12-bit resolution, 10 µs settling — the update-rate ceiling
The DAC121S101CIMKX/NOPB is a 12-bit voltage-output digital-to-analog converter in a TSOT-23-6 package. Its 10 µs settling time to ±0.5 LSB sets the maximum update rate — at 100 kSPS the output has settled before the next conversion starts, so the downstream ADC or actuator sees a stable voltage each cycle. The String DAC architecture guarantees monotonicity — the output never decreases for an increasing digital code, which matters in closed-loop control where a non-monotonic step could cause oscillation.
No separate analog supply or charge pump needed — the supply-referenced output swings rail-to-rail, using the full dynamic range of the supply. The voltage-buffered output can drive a 2 kΩ load to within 50 mV of the rails without an external op-amp. For higher current loads or longer traces, a unity-gain buffer after the output adds margin.
SPI/DSP interface — standard MCU integration
The 3-wire SPI-compatible interface (SCLK, DIN, SYNC) operates up to 30 MHz. The 16-bit word format is standard: the first four bits are control (power-down mode), the remaining 12 bits are the data. The DSP frame-sync mode lets it connect directly to a synchronous serial port without glue logic. No differential output — the single-ended voltage output references the supply rail. For noisy environments, a differential ADC after the DAC would need a single-ended-to-differential converter.
The SOT-23-6 Thin package has a junction-to-ambient thermal resistance around 200°C/W — at 5.5 V and 0.5 mA supply current the self-heating is under 1°C, so the ambient rating is the binding limit.