What is the difference between DC/DC converters and LDO regulators?

LDO Linear RegulatorsDC/DC Switching Regulators

Both of DC/DC converters and LDO regulators convert an input direct current into a different direct current. The way of converting direct currents differs from each other. DC/DC converters regulate electric power by turning on and off switching elements (FETs, etc.). On the other hand, LDO regulators regulate power supply by controlling on-resistance of FETs.

DC/DC converters are highly efficient in converting electricity by the switching control. Depending on conditions such as output current, the efficiency can reach about 95%. Instead, there are some disadvantages. First, output voltages from this type of regulators contain ripples and switching noise, not suitable for noise-sensitive devices. Second, due to their complex control method, many external components are necessary compared with LDO regulators. Designing PCBs using DC/DC converters tends to be more difficult and more cost-consuming than those using LDO regulators.

The control method of LDO regulators is simple, so designing PCBs is easy. However, the conversion efficiency is inferior to that of DC/DC converters. In order to convert 5 V into 3 V, the efficiency by LDO regulators is 60%, while DC/DC converters can achieve 90% or more. Besides, if dropout voltage and output current are large, heat dissipation must be considered.