Linear regulators drop excess voltage as heat. They are quiet electrically but inefficient when Vin is much higher than Vout.
Selection checklist
- Dropout: Vin must stay above Vout plus dropout at load current.
- Package and θJA: Estimate (Vin − Vout) × I as heat; add copper and heatsink if needed.
- Accuracy and noise: LDOs for RF and precision references; watch output capacitor requirements in the datasheet.
When dissipation is too high, move to a buck converter in the same rail family.