Switching Regulators (DC-DC Converters)

What is a Switching Regulator?

What is a switching regulator?

1. Basic role

A switching regulator (DC-DC converter) is a regulator (stabilized power supply). A switching regulator can convert input direct current (DC) voltage to the desired direct current (DC) voltage.
In an electronic or other device, a switching regulator takes the role of converting the voltage from a battery or other power source to the voltages required by subsequent systems.

As the illustration below shows, a switching regulator can create an output voltage (VOUT) that is higher (step-up, boost), lower (step-down, buck) or has a polarity different than that of the input voltage (VIN).

Image of Switching regulator VIN and VOUT

2. Switching regulator types

A switching regulator is a regulator (stabilized power supply) and there are the following switching regulator types.

(stabilized power supply)
(DC-DC converter)
  Isolated switching regulator
    Non-isolated switching regulator
  Shunt regulator
    LDO regulator

This article provides a detailed explanation of the features and operation of “non-isolated switching regulators.”

Non-isolated switching regulators also use the following systems and operating modes.

 Voltage conversion system Step-down, step-up, step-up/down, invert
Rectification system Asynchronous, synchronous
Operating mode PFM, PWM, PFM/PWM switching

Click the term to find out more.

3. Switching regulator characteristics

The following provides a description of non-isolated switching regulator characteristics.

High efficiency

Schematic drawing of a switching regulatorBy turning a switching element ON and OFF, a switching regulator enables high-efficiency electricity conversion as it supplies the required amount of electricity only when needed.

A linear regulator is another type of regulator (stabilized power supply), but because it dissipates any surplus as heat in the voltage conversion process between VIN and VOUT, it is not nearly as efficient as a switching regulator.

The easiest way of explaining how a switching regulator can efficiently convert voltage is comparing it to a linear regulator.

For example, if the input voltage (VIN)  is 5.0V, output voltage (VOUT) is 2.5V and load current (IOUT) is 0.1A,

In a linear regulator
Input power = Input voltage × Load current
                        = 5.0V × 0.1A
                        = 0.5W
Output power = Output voltage × Load current
                          = 2.5V × 0.1A
                          = 0.25W
Since efficiency = Output power ÷ Input power, the efficiency of a linear regulator is 50%.

Efficiency of linear regulator

A switching regulator, however, controls the period when the input voltage is supplied by turning the switching element ON and OFF so that VOUT becomes 2.5V. This time period when input voltage is supplied is

 VOUT   VIN  =  2.5V   5.0V  =  1   2 

From this we can see that voltage is supplied for half a period. Similarly, if you try to obtain efficiency from the input and output power, we get the following:

Input power = Input voltage × Load current × 1 2
                        = 5.0V × 0.1A × 1 2
                        = 0.25W

Input power = Output voltage × Load current
                        = 2.5V × 0.1A
                        = 0.25W

Calculating efficiency from the above equation: Efficiency = Output power ÷ Input power, we obtain a value of 100%. This is why a switching regulator provides high efficiency.
Efficiency of switching regulator*Since there are actual losses, the true figure is around 90%.


The switching element ON/OFF operations in a switching regulator cause sudden changes in voltage and current, and parasitic components that generate ringing, all of which introduce noise in the output voltage.

Using an appropriate board layout is effective in mitigating noise. For instance, optimizing the placement of capacitor and inductor and/or wiring. For more information on the mechanism of how noise (ringing) is generated and how it is controlled, refer to the Application Note “Step-Down Switching Regulator Noise Countermeasures.


Comparing switching regulator and linear regulator characteristics
  Switching regulator Linear regulator
Output voltage conversion system Step-down, step-up, step-up/down, invert Step-down only; VOUT must be less than VIN 
Efficiency High (negligible heat generation) Comparatively low (high heat generation)
Low when the difference between input and output voltage is large
Output current Large (high efficiency means high current) Small
Noise Large Small
Output ripple Present None
Required external components Many

The ideal switching regulator for any application

Ultra-compact DC-DC converter ideal for automotive cameras
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S-19902/3 Series


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For industrial equipment and housing appliances
12V / 24V input, ultra-compact Webshop (Sample purchase)

S-8580/1 Series


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For IoT / wearable devices
Ultra-high efficiency at light load, compact Webshop (Sample purchase)

S-85M0A Series


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Operating principles and modes of a switching regulator

Introduction – Switching Regulator ICs (DC-DC Converter ICs)