Linear vs. Switching Regulators

Learn how to decide if a low powered linear regulator or highly efficient switching regulator is a better option for your design.

Linear Regulators

Linear regulators are a great choice for powering very low powered devices or applications where the difference between the input and output is small. Even though they are easy to use, simple and cheap, a linear regulator is normally inefficient. The equation for dissipated power in a linear regulator is:

Power dissipation = (input voltage – output voltage) × load current

Switching Regulators

Switching regulators on the other hand are highly efficient and available as modular chips which are compact and reliable. Switching regulators can be further divided into isolated and non-isolated.

How do you choose?
  Linear Regulator Switching Regulator
Design Flexibility Buck Buck, Boost, Buck-Boost
Efficiency Normally low to medium-high for low difference between VIN-VOUT High
Complexity Low Medium to high
Size Small to medium, larger at high power Smaller at similar higher power (depending on the switching frequency)
Total Cost Low Medium to high – external components
Ripple/Noise/EMI Low Medium to high
VIN Range Narrow (depending on power dissipation) Wide

 

Linear Regulators

Linear Regulator Control

Positives: 
Simple, Low Cost, Low Noise

Negatives: 
Less Efficient, Power Dissipation, Power Capacity

Linear regulators use linear, non-switching techniques to regulate the voltage output from the power supply. The regulator’s resistance varies according to the load and results in a constant output voltage.

All linear regulators require an input voltage at least some minimum amount higher than the desired output voltage. That minimum amount is called the dropout voltage. A low-dropout or LDO regulator is a DC linear regulator which can regulate the output voltage even when the supply voltage is very close to the output voltage.

Linear regulators are a great choice for powering very low powered devices or applications where the difference between the input voltage and output voltage is small. They are a simple and cheap solution, but linear regulators are normally inefficient because the difference between the input voltage and regulated output voltage is continually dissipated as heat.

Intersil’s low drop-out regulators (LDO) generate low current, well-regulated outputs and require very few external components.

Intersil's Advantages

Small package, Small drop out, Fast transient response, High accuracy

Switching Regulators

Switching Regulator Control

Positives:
Efficient, High Power

Negatives:
Noisy, Complicated

Some of the key requirements of today’s power management solutions include less power consumption under various load conditions, less space, high reliability and wide input voltage. These requirements are driving the need for highly efficient, wide VIN, low quiescent current (IQ) switching regulators in a broad range of applications.

Switching regulators rapidly switches a series element on and off. They can operate with both synchronous and non-synchronous switches (FETs). These devices store the input energy temporarily and then releasing that energy to the output at a different voltage level. The switch’s duty cycle sets the amount of charge transferred to the load.

Switching regulators are efficient because the series element is either fully conducting or switched off so it dissipates almost no power. Switching regulators are able to generate output voltages that are higher than the input voltage or of opposite polarity, unlike linear regulators. The versatility of these converters allow configuration for buck, boost, buck-boost, flyback, inverting in isolated and non-isolated applications.

Integrated FET regulators are a subset of switching regulators. These microcircuits have integrated the power MOSFET and are considered a whole solution; whereas controllers employ external power MOSFETs. Both configurations are classified as switching regulators because they regulate the output voltage.

Intersil's Advantages

Wide input and output range, Integrated FET’s, Pin to pin compatible parts, Internal compensation, Light load efficiency mode, Simple and easy to use

Power Savings Between LDO and Switching Regulators

Efficiency Curve for LDO and Switching Regulators

Find a Linear or Switching Regulator

Linear Regulators

Intersil's standard and low-dropout (LDO) regulators provide a variety of simple, low cost and low noise solutions.

View linear regulator products »

Switching Regulators

Intersil offers a wide range of step-down (buck), buck-boost, step-up (boost) switching regulators that operate with both synchronous and non-synchronous internal switches (FETs).

View switching regulator products »

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