Step Down converter or commonly known as a Buck converter is an essential part of any electronic design, it's a type of DC-DC converter that can convert the higher voltage to lower voltage very efficiently. With an efficient power supply, you can achieve objectives like long battery life (for battery-powered applications), reduced thermals & long life for the whole circuit. But choosing the right Buck Voltage Regulator for a specific application can be a daunting task. So, let us make this article an opportunity to find out some of the smallest, cheapest, and commonly used buck regulators available in the market apart from the most popular and commonly used ICs, like LM2576, XL6009, CS51411, etc. You can also check out how to select Linear regulator IC if you also want to explore other regulators other than buck regulators. 

 

Buck Converter - Basics

We have already discussed the Basics of Buck Regulators and how they work, but before we take a look at some of the buck regulators, let's clarify the basic concept first. When the MOSFET is on, the voltage appears across the inductor, as current in the inductor cannot rise instantaneously, it will rise slowly. At this point, Diode D is in reverse biased condition and not conducting.

 

When the switch opens, the current still flows as the inductor tries and opposes the change in current, as a result, the polarity of the voltage across the inductor is now in the reverse direction, therefore, the current through the inductor decreases, decreasing the output voltage.                                

 

Top 10 Modern Day Buck Regulator ICs

 

#10 – LM2576 by Texas Instruments

The LM2576 is an industrial standard, low-cost, single-chip, readily available step-down (buck) switching regulator, which has a max input voltage of 37V for the non-HV version and 60V for the HV version. 

 

To meet the market requirement, there are two different output voltage variants available, one is fixed, and another is adjustable. As for the output current, this IC can handle a maximum 3A constant load with a proper heat sink, to know more about different output voltage options and packaging information, please refer to the datasheet of this IC.

 

With a switching frequency of 52KHz, this IC can achieve 90% efficiency with low input voltage and low output current draw. With a 3A constant load, this IC can reach an efficiency of 77% in the worst-case scenario.

 

Protection Features: Thermal shutdown and current limit

 

Other Features: TTL-Shutdown Capability, Low-Power Standby Mode.

 

Applications: Battery Charger, High-Efficiency Step-Down, Efficient Preregulator for Linear Regulators, Positive-to-Negative Converter & more.

 

Datasheet: LM2576 Datasheet

 

#9 – RT6200 by Richtek

The RT6200 is an improved, low cost, single-chip, readily available step-down (buck) regulator, the input voltage range of this IC is 4.5V - 36V.

 

The output voltage of this IC can be adjusted to anywhere between 0.8V - 5V. With a 0.35Ω internal power MOSFET, this IC can provide a max output current of 0.6A. Please refer to the datasheet of this IC for more details.

 

With a fixed switching frequency of 1.2MHz, this IC can reach 95% efficiency with low input voltage and low output current draw. With a 0.6A constant current, this IC can achieve an efficiency of 85% in the worst-case scenario.

 

Protection Features: Include thermal shutdown and Cycle-By-Cycle Over-Current Protection.

 

Other Features: TTL-Shutdown Capability, Low-Power Standby Mode.

 

Applications: Battery Charger, Distributed Power Systems, Pre-Regulator for Linear Regulators, WLED Drivers & more.

 

Datasheet: RT6200 Datasheet

 

#8 – RT5707/A by Richtek

The RT5707 is another new, low cost, single-chip, readily available step-down (buck) regulator, the input voltage range of this IC is 2.2V - 5.5V, and with a dimension specification of 1.56 mm x 0.860 mm x 0.5 mm, this IC is practically tiny.

 

The output voltage of this IC can be adjusted to anywhere between 1.2V - 3.3V for the RT5707 version, and 0.7V to 3.1V for the RT5707A version. With a 0.6Ω internal MOSFET, this IC can reach a max output current of 0.6A and 1A at peak. Please refer to the datasheet of this IC for more details.

 

With a fixed switching frequency of 1.2MHz, this IC can reach 94% efficiency with low input voltage and low output current draw. With a 0.6A constant load, this IC can achieve an efficiency of 88% in the worst-case scenario.

 

Protection Features: Thermal shutdown and Cycle-By-Cycle Over-Current Protection.

 

Other Features: Ultra-Low Quiescent Current of 360nA, Advanced PFM (Pulse Frequency Modulation) Control, Hysteresis Constant-On-Time (HCOT) operation with internal compensation.

 

Applications: Hand-Held Devices, Portable Information, Battery-Powered Equipment, Wearable Devices, Internet of Things & more.

 

Datasheet: RT5707 Datasheet

 

#7 – MPM3610 by Monolithic Power Systems

The MPM3610 is a very modern, single-chip, step-down (buck) regulator that has an input voltage range of 4.5V to 21V. With a small QFN-20 package dimension, this IC can be used for ultra-compact applications.

 

The output voltage of this IC can be adjusted to anywhere between 0.8V - 28V. With a 40-mΩ or 0.004Ω internal power MOSFET, this regulator can handle an output current of 1.2A continuously. Please refer to the datasheet of this IC for more details.

 

This IC can achieve more than 93% efficiency at lighter load conditions, but with a constant load of 1.2A, the efficiency drops down to 65%.

 

As this is a very new IC that features some unique features, it doesn't need any inductors, capacitors, or diodes as external components, as these components are already built into it. To operate functionally, we need to add two feedback resistors in a voltage divider configuration to set the output voltage.

 

Protection Features: Overload protection with hiccup mode & thermal Shutdown.

 

Applications: Portable Devices, Digital Cameras and Camcorders, CD Players & more.

 

Datasheet: TPS54232 Datasheet

 

#6 – SY8105ADC by Richtek

The SY8105ADC is a new, low-cost, single-chip, buck regulator IC with an input voltage range of 4.5V - 18V.

 

The output voltage of this IC can be adjusted anywhere between 0.8V - 18V, and with a 40mΩ internal power MOSFET, this IC can achieve a max output current of 5A. Please refer to the datasheet of this IC for more details.

 

This IC has a fixed switching frequency of 500KHz. With that, it can achieve an efficiency of 95%, assuming low input voltage and low output current draw. With 5A constant load efficiency drops to 50%.

 

Protection Features: Thermal shutdown and Cycle-By-Cycle Over-Current Protection.

 

Other Features: Thermal Protection, Internal soft-start, and more.

 

Applications: Battery Charger, Set-Top Box, Portable TV, DSL Modem & more.

 

Datasheet: SY8105ADC Datasheet

 

#5 – TPS54302DDCR by Texas Instruments

The TPS54302DDCR is another new, low-cost, single-chip, step-down (buck) regulator, with an input voltage range of 4.5V - 28V.

 

This IC has a fixed switching frequency of 400KHz, with that it can achieve an efficiency of 80% considering low input voltage and low output current load. With 2A constant load, this IC can reach an efficiency of 95%.

 

Other features include Over Voltage Protection, Internal Loop Compensation, Peak Current Mode Control, Advanced Eco-mode with Pulse Skip Functionalities, Frequency Spread Spectrum to Reduce EMI & Noise, Low 2-μA Shutdown, 45-μA Quiescent Current, and Internal 5-mS Soft-Start functionality.

 

Protection Features: Built-in Transient Protection, Cycle-by-Cycle Current Limit, Frequency Foldback, and Thermal Shutdown Protection.

 

Applications: Portable Devices, Digital Cameras and Camcorders, CD Players & more.

 

Datasheet: TPS54302DDCR Datasheet

 

#4 – A4490 by Allegro Microsystems

The A4490 is another new, low-cost, single-chip, step-down (buck) regulator that has an input voltage range of 4.5V - 34V. With a dimension specification of 4 mm × 4 mm, 0.75 mm QFN. This IC is designed for modern-day compact applications.

 

As this is a unique type of IC, it features three adjustable outputs & all three outputs can be independently set anywhere between 0.8V to 34V. With an 80-mΩ or 0.008Ω internal power MOSFET, all three are capable of delivering 1.5A. Please refer to the datasheet of this IC for more details.

 

This IC has a fixed switching frequency of 550KHz. It can achieve an efficiency of 90% with low input voltage and low output current draw. With 1.5A constant load, the efficiency drops to 75%.

 

Other Features: Multiphase switching, Independent control for each regulator, Power-on-reset flag, Internal compensation.

 

Protection Features: Thermal Protection, Undervoltage Lockout Start-up, Undervoltage Lockout Shutdown & Overload Protection.

 

Applications: Portable Devices, Digital Cameras and Camcorders, Photo, inkjet, portable printers & more.

 

Datasheet: A4490 Datasheet

 

#3 – TPS65400 by Texas Instruments

The TPS65400 is an advanced, single-chip step-down (buck) regulator that has an input voltage range of 4.5V - 18V. With a dimension specification of Thermally-Enhanced 7-mm × 7-mm 48-Pin, 0.5- mm Pitch VQFN Package. This small IC comes with four high current output stages and its design for modern-day compact applications.

 

As this is a unique IC, it features four adjustable outputs & the output voltage can be set anywhere between 0.6V to 18V. The SW1 & SW2 outputs of this IC are capable of delivering a max current of 4A and as for SW3 & SW4, the maximum current rating is 2A.

 

This IC has a resistor adjustable PWM switching frequency from 275 kHz to 2.2 MHz, which means the user can program the switching frequency according to need. With that, this IC can achieve an efficiency of 95% considering low input voltage and low output current draw. With max constant load, the efficiency of this device drops to 75%.

 

This IC has many unique features like Pre-Bias Start-up Algorithm through which it minimizes voltage dip during Start-up, Sequencing Control through precision enable pins for each switcher, Clock Sync Input and Clock Output, Soft-Start Delay through external capacitor current sharing between SW1 and SW2 and between SW3 and SW4 allows support of higher current needs if required, – Runtime Voltage Positioning through adjustment of VREF enable and disable of each switcher fault and status monitoring & more. Please refer to the datasheet for more information.

 

Protection Features: Internal Undervoltage Lockout (UVLO), Overcurrent Protection (OCP), Overvoltage Protection (OVP), and Overtemperature Protection (OTP).

 

Applications: Portable Devices, Digital Cameras and Camcorders, Photo, inkjet, portable printers & more.

 

Datasheet: TPS65400 Datasheet

 

#2 – RT9992 by Richtek

The RT9992 is another advanced, single-chip, step-down (buck) regulator, the input voltage range of this IC is 2.7V - 5.5V. With a dimension specification of 4 mm × 4 mm, 0.75 mm nominal overall height QFN, with exposed pad for enhanced thermal dissipation. This IC is practically tiny, and its design for modern-day compact applications.

 

As this is a special type of IC, it features five independent switching regulators, a synchronous step-up, a selectable synchronous step-up/step-down, two synchronous step-downs, and one WLED driver in either asynchronous step-up mode or current source mode. Besides that, there are two other LDO, the first one is the RTC LDO and the second one is a generic LDO. The maximum current rating of this IC is 4A. Please refer to the datasheet for output voltage options and example circuits.

 

This IC has an adjustable switching frequency of 1MHz - 3MHz which can be adjusted by two external feedback resistors. This IC can reach an efficiency of 95%, assuming a constant current load of 1A. With 4A constant load, the efficiency drops to 83%.

 

Other Features: Bootstrap operation, Independent VIN Supplies for Each DC/DC, Precision Enable Pin Thresholds for Autonomous Sequencing, Die Temperature Monitor Output.

 

Protection Features: Thermal Protection, Undervoltage Lockout Startup, Undervoltage Lockout Shutdown & Overload Protection.

 

Applications: Digital Cameras and Camcorders, General Purpose Multi-Channel Power Supplies, Industrial/Automotive/Communications applications & more.

 

Datasheet: RT9992 Datasheet

 

#1 – LTC3374 by Analog Devices

The LTC3374 is another advanced, low-cost, single-chip, step-down (buck) regulator that has an input voltage range of 2.5V - 5.5V. With a QFN package dimension of 5 mm × 7 mm, 0.75 mm. This IC is designed for modern-day compact applications.

 

As this is a special type of IC, it features eight adjustable output ports. The output voltage of every output port can be set anywhere between 0.8V to 5.5V. With an 80-mΩ or 0.008Ω internal power MOSFET, all eight outputs are capable of delivering 4A of current from each output port. Please refer to the datasheet of this IC for more details.

 

This IC has a fixed switching frequency of 550KHz. With that, this IC can reach an efficiency of 90%, considering low input voltage and low output current draw. With 1.5A constant load, the efficiency drops down to 75%.

 

Other Features: Multiphase switching, Independent control for each regulator, Power-on-reset flag, Internal compensation.

 

Protection Features: Thermal Protection, Undervoltage Lockout Start-up, Undervoltage Lockout Shutdown & Overload Protection.

 

Applications: Portable Devices, Digital Cameras and Camcorders, Photo, inkjet, portable printers & more.

 

Datasheet: LTC3374 Datasheet