Buck Converters

A Buck Converter, also known as a Step-Down Converter, is a DC-to-DC power converter that steps down the voltage from its input to its output. A buck converter integrates the core components and circuitry needed into a single device.

Buck converters are found in countless electronic applications, where their power regulation properties are a vital component.

How does a Buck Converter work?

A Buck Converter is a type of switch-mode power supply, a class of device that incorporates a switch (e.g. typically a MOSFET) to rapidly turn the circuit on and off. This rapid switching creates a square wave. If the duty cycle of the switch is set to 50%, i.e. the switch is on 50% of the time, the average voltage will be 50% of the input.

The square wave needs to be smoothed to provide useful power, typically an inductor and capacitor are used in series to fulfil this function. This combination is called an LC low pass filter. The properties of an inductor smooth the current flow, while the capacitor resists sudden changes in voltage. The combined effect produces a relatively smooth voltage output with low ripple. For example, if the input voltage is 10V and the switch employs a duty cycle of 50%, the output voltage will be 5V.

A further necessary component of a Buck Converter is to incorporate a diode or other switch in parallel with the inductor. This is to compensate for the property of an inductor, in that the current in an inductor cannot instantly change, protecting the switching transistor from being overloaded and destroyed.

Buck Converters also incorporate additional circuitry to ensure a stable output voltage. The converter uses a closed-loop control scheme with negative feedback to monitor the voltage output and dynamically adjusts the duty cycle of the switch to regulate the output voltage.

Design considerations

  • Buck Converters are very efficient, with some devices offering efficiencies of above 95%.
  • Buck Converters can be more cost-effective than linear regulators at higher power levels, the cost of removing the heat generated by a linear regulator may be less than employing a Buck Converter.
  • The output of a Buck Converter will feature a noise, meaning the more stable output of a linear voltage regulator is better suited for application requiring low output noise.
  • Linear regulators can respond faster to input and output changes versus a buck converter.

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Description Price Maximum Output Current Maximum Output Voltage Regulator Function Minimum Output Voltage Minimum Input Voltage Maximum Input Voltage Output Type Mounting Type Series Number of Outputs Pin Count Package Type Switching Regulator Line Regulation
RS Stock No. 127-0660
Mfr. Part No.L296P
MYR31.13
Each
units
4A 40 V Buck Controller 5.1 V 9 V 46 V Adjustable Through Hole - 1 15 MULTIWATT V Yes 50 mV
RS Stock No. 178-1391
Mfr. Part No.L296P
MYR27.396
Each (In a Tube of 25)
units
4A 40 V Buck Controller 5.1 V 9 V 46 V Adjustable Through Hole - 1 15 MULTIWATT V Yes 50 mV
RS Stock No. 168-6046
Mfr. Part No.L4962/A
MYR14.10
Each (In a Tube of 25)
units
- 40 V Buck Controller 5.1 V 9 V 46 V Adjustable Through Hole - 1 16 PDIP Yes 50 mV
RS Stock No. 168-5905
Mfr. Part No.L4960
MYR13.577
Each (In a Tube of 50)
units
- 40 V Buck Controller 5.1 V 9 V 46 V Adjustable Through Hole - 1 7 HEPTAWATT V Yes 50 mV
RS Stock No. 686-8464
Mfr. Part No.VIPER16LN
MYR3.98
Each (In a Pack of 5)
units
- - - - - - - Through Hole - - 7 PDIP - -
RS Stock No. 380-034
Mfr. Part No.L5973D
MYR13.23
Each (In a Pack of 5)
units
2A 35 V Buck Controller 1.235 V 4 V 36 V Adjustable Surface Mount - 1 8 HSOP Yes 10 mV
RS Stock No. 127-0676
Mfr. Part No.L4960
MYR15.98
Each
units
- 40 V Buck Controller 5.1 V 9 V 46 V Adjustable Through Hole - 1 7 HEPTAWATT V Yes 50 mV
RS Stock No. 102-3574
Mfr. Part No.L5973D
MYR6.979
Each (In a Tube of 100)
units
2A 35 V Buck Controller 1.235 V 4 V 36 V Adjustable Surface Mount - 1 8 HSOP Yes 10 mV
RS Stock No. 177-3614
Mfr. Part No.L4962/A
MYR16.81
Each
units
- 40 V Buck Controller 5.1 V 9 V 46 V Adjustable Through Hole - 1 16 PDIP Yes 50 mV
RS Stock No. 178-1480
Mfr. Part No.VIPER16LN
MYR3.381
Each (In a Tube of 50)
units
- - - - - - - Through Hole - - 7 PDIP - -
RS Stock No. 102-3576
Mfr. Part No.L4973D5.1
MYR16.422
Each (In a Tube of 40)
units
3.5A - Buck Controller - 8 V 55 V Adjustable Surface Mount - 1 20 SOIC Yes 10 mV
RS Stock No. 168-6475
Mfr. Part No.VIPER16LD
MYR3.261
Each (In a Tube of 50)
units
- - - - - - - Surface Mount - - 16 SOIC - -
RS Stock No. 686-8275
Mfr. Part No.L4963D
MYR24.09
Each
units
- 36 V Buck Controller 5.1 V 9 V 46 V Adjustable Surface Mount - 1 20 SOIC Yes 50 mV
New
RS Stock No. 216-7848
Mfr. Part No.L6981CDR
MYR4.994
Each (On a Reel of 2500)
units
1.5A 8 V Buck -0.3 V 3.5 V - Adjustable - - 1 8 SO8 - -
RS Stock No. 203-3423
Mfr. Part No.ST1PS01AJR
MYR3.849
Each (On a Reel of 5000)
units
400mA 3.3 V Synchronous Buck Converter 1.8 V 1.8 V - Selectable - - 1 8 Flip-Chip - -
RS Stock No. 379-993
Mfr. Part No.L5972D
MYR12.534
Each (In a Pack of 5)
units
1.5A 35 V Buck Controller 1.235 V 4.4 V 36 V Adjustable Surface Mount - 1 8 SOIC Yes -
New
RS Stock No. 212-2098
Mfr. Part No.ST1PS01FJR
MYR7.20
Each (In a Pack of 5)
units
400mA 3.3 V Step Down 1.05 V 1.8 V - Fixed - - 1 8 Flip-Chip - -
RS Stock No. 165-5532
Mfr. Part No.ST1S03PUR
MYR3.125
Each (On a Reel of 3000)
units
- - - - 3 V 16 V Adjustable Surface Mount - - 6 DFN - 0.06 %
New
RS Stock No. 218-4845
Mfr. Part No.ST1PS02C1QTR
MYR3.248
Each (On a Reel of 3000)
units
400mA 3.3 V Step Down -0.3 V 1.8 V - Selectable - - 2 12 TQFN12 - -
New
RS Stock No. 210-2037
Mfr. Part No.ST1PS02BQTR
MYR3.802
Each (On a Reel of 3000)
units
400mA 3.3 V Step Down 1 V 1.8 V - Adjustable - - 2 12 TQFN - -