Deciding when to use voltage regulators or DC/DC converters

This section explains how to decide whether to use a linear voltage regulator or a switching DC/DC converter.

First, let’s review the advantages and disadvantages of the linear voltage regulator.

Linear voltage regulator advantages

• The design is simple, operating by only connecting capacitors to both the input and output sides.
• Low noise
• Few components, saves space
• Low price
• There are many products, making it easy to select an optimal one.

Linear voltage regulator disadvantages

• The loss is large and the efficiency poor when there is a large difference between the input voltage and the output voltage.
• A large amount of heat is generated when the difference between the input voltage and the output voltage is large, so measures to dissipate the heat are required.
• Only step-down operations (lowering the voltage) are possible.

To determine whether to use a voltage regulator or a switching DC/DC converter, if the voltage regulator disadvantages can be tolerated, then selecting the linear voltage regulator is the optimum option.

The conditions for using a switching DC/DC converter are as follows.

In all other cases, using a linear voltage regulator is best.

Conditions when a DC/DC converter should be used

(a)Power supply configuration

• A power supply configuration other than step-down (step-up, step-up/down, polarity reverse) is required.

(b)Heat related

• A voltage regulator cannot be used due to the heat generated in the IC.
• Overall system heat generation must be kept down.
• It is desirable that heat countermeasure components, such as a heat sink, to lower the cost and save space used by the overall system.

(c)Loss and efficiency related

• Reducing the voltage regulator loss is desired to increase the battery operation life.
• Using a high efficiency DC/DC converter is required to reduce the overall power consumption of the device.

	Voltage Regulator (Linear type)	DC/DC Converter (Switching type)
Simple to design	Good	Normal
Number of parts/space saving	Good	Normal
Price	Low	Normal
Noise	Good	Bad
Efficiency	Bad	Good
Heat generation	Bad	Good
Battery life	Short	Long
Power supply configuration	Step-down	Step-down/Step-up etc