Last revised: November 15, 2024

Reviewed by: Scott Orlosky, consulting engineer

IC switching voltage regulators are integrated circuits (ICs) that store energy in an inductor, transformer, or capacitor and then use this storage device to transfer energy from the input to the output in discrete packets over a low-resistance switch.

Feedback circuitry regulates the energy transfer to maintain a constant voltage within the load limits of the circuit.

Types of Voltage Regulators

There are several types of IC switching voltage regulators.

• Buck or step-down converters convert a higher DC input voltage to a lower DC output voltage of the same polarity.
• Boost or step-up converters convert a lower DC input voltage to a higher DC output voltage of the same polarity.
• Buck-boost converters can be used for either step-up or step-down conversions, and to reverse or invert voltage polarity.

IC switching voltage regulators are more efficient than IC linear voltage regulators, but produce greater amounts of noise.  

IC Switching Voltage Regulators Specifications

Important specifications for IC switching voltage regulators include regulated output voltage, input voltage, output current, switching frequency, efficiency, duty cycle and operating temperature.

• Both the output regulated voltage (V_OUT) and the input voltage (V_IN) are minimum and maximum amounts in continuous mode (DC). The output voltage can be fixed, or adjusted to a value within a specified range.
• The output current (I_OUT) is measured under specified conditions.
• Efficiency, the ratio of output power to input power, measures the ability of IC switching voltage regulators to convert input energy into output energy. For example, an efficiency of 100% means that all of the input energy is transferred to the output.
• The duty cycle is the ratio between the on and off time of the output transistor.
• The operating temperature is specified as a full-required range.  

Features

IC switching voltage regulators are available with a variety of features. Features may include:

• More than one output or channel.
• An internal circuit to control the amount of current produced, or an error flag for monitoring outputs that drop below a nominal value.
• Reverse voltage protection prevents damage in applications where users can accidentally reverse battery polarity.
• Thermal shutdown protection turns off IC switching regulators when the temperature exceeds a predefined limit.
• Shutdown (inhibit) pins are used to disable regulator outputs.

Packaging

IC switching voltage regulators are available in a variety of IC package types.

• Dual in-line packages (DIP) can be made of ceramic (CIP) or plastic (PDIP).
• Quad flat packages (QFPs) contain a large number of fine, flexible, gull wing shaped leads. SC-70, one of the smallest available IC packages, is well-suited for applications where space is extremely limited.
• Small outline (SO) packages are available with 8, 14, or 20 pins.
• Transistor outline (TO) packages are commonly available. TO-92 is a single in-line package used for low power devices. TO-220 is suitable for high power, medium-current, and fast-switching products. TO-263 is the surface-mount version of the TO-220 package.
• Other IC packages for IC switching voltage regulators include shrink small outline package (SSOP), small outline integrated circuit (SOIC), small outline package (SOP), small outline J-lead (SOJ), discrete package (DPAK), and power package (PPAK).

Standards

MIL-STD-883 Voltage regulators must adhere to standards to ensure proper design and functionality. Example of testing standards.

IC Switching Voltage Regulators FAQs

How do IC Switching Voltage Regulators compare to linear voltage regulators in terms of efficiency?

Switching voltage regulators generally offer higher efficiency compared to linear voltage regulators. The efficiency of switching regulators typically starts at about 60% and can reach 90% or higher, depending on the application and load conditions.

Linear voltage regulators, on the other hand, have efficiency levels ranging from about 50% to 70%.

Switching regulators achieve high efficiency by using a high-frequency switching technique, which allows them to supply power only when needed.

Linear regulators operate continuously, dissipating excess voltage as heat, which results in lower efficiency, especially when there is a large voltage differential between input and output.

The efficiency of switching regulators can decrease significantly when operating at less than 60-80% of their rated load.

Linear regulators can be more competitive at very low current levels and power levels under about 10 W, where their simplicity and low noise can be advantageous.

For applications requiring higher power levels (above several amps and power ratings of about 25 to 50 W), switching regulators are generally preferred due to their efficiency and lower power dissipation.

In contrast, for low-power applications, linear regulators might be chosen for their simplicity and low noise characteristics.

How do switching regulators manage heat dissipation compared to linear regulators?

Switching regulators manage heat dissipation more effectively due to their operational mechanism. They achieve high efficiency by using a high-frequency switching technique, which allows them to supply power only when needed, thereby reducing wasted power and heat generation.

Linear regulators, on the other hand, dissipate excess voltage as heat because they operate continuously at a 100% duty cycle. This means that any voltage difference between the input and output is converted into heat, leading to higher heat dissipation.

Power dissipation in linear regulators is calculated using the formula: 

PD = ( VIN - VOUT ) x IOUT

This means that power dissipation is a function of the voltage differential time the current output.

Switching regulators avoid this by only transmitting the required power to the output side, thus minimizing heat generation.

What are the noise characteristics of switching versus linear regulators?

Switching regulators tend to be much noisier than linear regulators due to their inherent switching action. This noise can affect power rails used with or near components or circuits that are sensitive to any noise on their DC rails or transferred through induction.

Linear regulators are almost noise-free, making them suitable for applications where low noise is critical.

Some switching regulators are designed for ultra-low noise output, with a noise figure of merit that is quite close to that of linear regulators (LDOs). This makes them more suitable for noise-sensitive applications while still benefiting from the efficiency of switching regulators.

The choice between switching and linear regulators often depends on the specific requirements of the application. For applications where noise is a critical factor, linear regulators might be preferred. However, if efficiency is a higher priority and noise can be managed or mitigated, switching regulators might be considered.

What is the impact of load conditions on the efficiency of switching regulators?

Switching regulators generally exhibit high efficiency, reaching up to 90% or higher. However, their efficiency can decrease significantly when operating below their rated load (in the 60 -80 % level). Switching regulators are most efficient when they are operating near their full load capacity. However, at very low power levels, linear regulators might be more competitive due to their simplicity and low noise characteristics.

The duty cycle of the load also affects the overall energy consumption and efficiency of switching regulators. A higher duty cycle, where the load is active for a larger portion of the time, can lead to better efficiency compared to a lower duty cycle.

Switching regulators operate by rapidly switching the input voltage on and off, a process known as "chopping" the input DC voltage. This allows them to transmit only the required power to the output side, which contributes to their high efficiency. The switching action inherently generates electrical noise, which can affect sensitive components or circuits nearby.

Due to their high efficiency, switching regulators manage heat dissipation more effectively than linear regulators. They only supply power when needed, reducing power wastage and heat generation.

Linear regulators operate continuously at a 100% duty cycle, meaning the input is never turned off. They dissipate excess voltage as heat, which results in lower efficiency, especially when there is a large voltage differential between input and output.

They are less efficient than switching regulators because they convert the voltage difference between input and output into heat. The efficiency of linear regulators ranges from about 50% to 70%.

However, linear regulators are almost noise-free, making them suitable for applications where low noise is critical.

What are the applications where switching regulators are preferred?

Switching regulators are almost always the best choice for applications with current requirements above several amps and power ratings of about 25 to 50 W or higher. This is due to their efficiency and consequent low power dissipation, which makes them suitable for high-power applications.

They are preferred in scenarios where efficiency is a critical factor. Switching regulators can achieve efficiency levels up to 90% or higher, making them suitable for applications where minimizing power loss is essential.

High efficiency means better heat management than linear regulators. This makes them ideal for compact or thermally sensitive environments.

Switching regulators are most efficient when operating near their full load capacity. They are preferred in applications with consistent mid to high load conditions where maintaining high efficiency is important.

They are suitable for applications where the input voltage can vary significantly, as they can efficiently convert a wide range of input voltages to a stable output voltage.

IC Switching Voltage Regulators Media Gallery

References

Electronics360—DC-DC Voltage Regulators: Key to Reliable Circuit Performance

Electronics360—How to select a voltage regulator

Image Credits:

Fuji Electric Corp. of America | ROHM Semiconductor USA LLC