What are the types of voltage references and their key specifications?

Voltage reference types include: Bandgap references (1.25V typical, using silicon bandgap voltage, temperature-compensated), Zener references (higher voltage, lower precision), and Buried Zener (premium precision). Key specifications are: Initial accuracy (0.02% to 2%), Temperature coefficient (1-100 ppm/C), Long-term stability (drift over years), Noise (affects ADC performance), Line regulation, and Load regulation. For precision applications, choose bandgap references with curvature compensation achieving <10 ppm/C, and consider thermal hysteresis effects.