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. 533-5266
Mfr. Part No.LM2678T-12/NOPB
MYR27.02
Each
units
5A - Buck Controller - 8 V 40 V Fixed Through Hole - 1 7 TO-220 Yes -
RS Stock No. 920-3665
Mfr. Part No.LM2675M-5.0/NOPB
MYR20.055
Each (In a Tube of 95)
units
1A - Buck Controller - 8 V 40 V Fixed Surface Mount - 1 8 SOIC Yes -
RS Stock No. 825-3684
Mfr. Part No.TLV62130RGTR
MYR6.836
Each (In a Pack of 5)
units
3A 5 V Buck Converter 0.9 V 4 V 17 V Adjustable Surface Mount - 1 16 QFN - 0.02 %/V
RS Stock No. 533-3197
Mfr. Part No.LM2576S-12/NOPB
MYR12.87
Each
units
3A - Buck Controller, Inverting - 4 V 40 V Fixed Surface Mount - 1 5 D2PAK (TO-263) Yes -
RS Stock No. 920-3517
Mfr. Part No.LM2576S-12/NOPB
MYR10.952
Each (In a Tube of 45)
units
3A - Buck Controller, Inverting - 4 V 40 V Fixed Surface Mount - 1 5 D2PAK (TO-263) Yes -
RS Stock No. 786-2394
Mfr. Part No.LM2596DSADJG
MYR10.90
Each (In a Pack of 5)
units
3A 37 V Buck Controller 1.23 V 4.5 V 40 V Adjustable Surface Mount - 1 5 D2PAK Yes -
RS Stock No. 121-6368
Mfr. Part No.LM2596DSADJG
MYR9.198
Each (In a Tube of 50)
units
3A 37 V Buck Controller 1.23 V 4.5 V 40 V Adjustable Surface Mount - 1 5 D2PAK Yes -
RS Stock No. 910-1581
Mfr. Part No.MIC4680YM
BrandMicrochip
MYR8.485
Each (In a Pack of 2)
units
1.3A - Buck Controller 1.25 V 4 V 34 V Adjustable Surface Mount - 1 8 SOIC Yes -
RS Stock No. 908-3871
Mfr. Part No.LMR14020SDDA
MYR11.27
Each (In a Pack of 2)
units
2A 28 V Step Down 0.8 V 4 V 40 V Adjustable Surface Mount - 1 8 SOIC Yes -
RS Stock No. 533-3614
Mfr. Part No.LM2595S-5.0/NOPB
MYR19.92
Each
units
1A - Buck Controller, Inverting - 4.5 V 40 V Fixed Surface Mount - 1 5 D2PAK (TO-263) Yes -
RS Stock No. 146-0313
Mfr. Part No.MIC4680YM
BrandMicrochip
MYR7.953
Each (In a Tube of 95)
units
1.3A - Buck Controller 1.25 V 4 V 34 V Adjustable Surface Mount - 1 8 SOIC Yes -
RS Stock No. 545-5219
Mfr. Part No.LT1076CQ#PBF
MYR40.15
Each
units
2A 50 V Buck Controller 2.5 V 7.3 V 45 V Adjustable Surface Mount - 1 6 D2PAK Yes 0.02 %/V
RS Stock No. 162-9813
Mfr. Part No.LMR14020SDDA
MYR10.147
Each (In a Tube of 75)
units
2A 28 V Step Down 0.8 V 4 V 40 V Adjustable Surface Mount - 1 8 SOIC Yes -
RS Stock No. 920-3514
Mfr. Part No.LM2576S-ADJ/NOPB
MYR13.136
Each (In a Tube of 45)
units
3A 37 V Buck Controller, Inverting 1.23 V 4 V 40 V Adjustable Surface Mount - 1 5 D2PAK (TO-263) Yes -
RS Stock No. 125-3772
Mfr. Part No.LTM4625EY#PBF
MYR63.77
Each
units
5A 5.5 V Step Down 0.6 V 4 V 20 V dc Adjustable Surface Mount - 1 25 BGA Yes 0.15 %/V
RS Stock No. 920-3508
Mfr. Part No.LM2576HVT-ADJ/NOPB
MYR23.93
Each (In a Tube of 45)
units
3A 57 V Buck Controller, Inverting 1.23 V 4 V 60 V Adjustable Through Hole - 1 5 TO-220 Yes -
RS Stock No. 460-487
Mfr. Part No.LM2576HVS-ADJ/NOPB
MYR29.53
Each
units
3A 57 V Buck Controller, Inverting 1.23 V 4 V 60 V Adjustable Surface Mount - 1 5 D2PAK (TO-263) Yes -
RS Stock No. 911-3108
Mfr. Part No.LM2575-5.0WT
BrandMicrochip
MYR9.944
Each (In a Pack of 5)
units
1A 5.25 V Step Down 4.75 V 4 V 40 V Fixed Through Hole - 1 5 TO-220 Yes -
RS Stock No. 178-4932
Mfr. Part No.LM2575-5.0WT
BrandMicrochip
MYR8.274
Each (In a Tube of 50)
units
1A 5.25 V Step Down 4.75 V 4 V 40 V Fixed Through Hole - 1 5 TO-220 Yes -
RS Stock No. 463-458
Mfr. Part No.LM2576T-005G
MYR9.16
Each (In a Pack of 2)
units
3A 5.25 V Buck Controller, Inverting 4.75 V 7 V 40 V Fixed Through Hole - 1 5 TO-220 Yes -