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. 146-5626
Mfr. Part No.LNK304PN
€0.657
Each (In a Tube of 50)
units
170mA 700 V Boost, Buck, Flyback -0.3 V 85 V ac 265 V ac Fixed Through Hole - 1 7 DIPB - -
RS Stock No. 920-3595
Mfr. Part No.LM2596S-ADJ/NOPB
€4.314
Each (In a Tube of 45)
units
3A 37 V Buck Controller, Inverting 1.2 V 4.5 V 40 V Adjustable Surface Mount - 1 5 D2PAK (TO-263) Yes -
RS Stock No. 533-3715
Mfr. Part No.LM2596S-ADJ/NOPB
€5.08
Each
units
3A 37 V Buck Controller, Inverting 1.2 V 4.5 V 40 V Adjustable Surface Mount - 1 5 D2PAK (TO-263) Yes -
RS Stock No. 779-9246
Mfr. Part No.LT1374HVCR#PBF
€10.09
Each
units
4.5A 5 V Buck Controller - 5 V 32 V - Surface Mount - 1 7 D2PAK Yes 0.03 %/V
RS Stock No. 920-3586
Mfr. Part No.LM2596S-5.0/NOPB
€4.20
Each (In a Tube of 45)
units
3A - Buck Controller, Inverting - 4.5 V 40 V Fixed Surface Mount - 1 5 D2PAK (TO-263) Yes -
RS Stock No. 533-3692
Mfr. Part No.LM2596S-5.0/NOPB
€4.95
Each
units
3A - Buck Controller, Inverting - 4.5 V 40 V Fixed Surface Mount - 1 5 D2PAK (TO-263) Yes -
RS Stock No. 533-8057
Mfr. Part No.LM2575T-12/NOPB
€2.26
Each
units
1A - Buck Controller, Inverting - 4 V 40 V Fixed Through Hole - 1 5 TO-220 Yes -
RS Stock No. 121-8702
Mfr. Part No.LM2575T-12/NOPB
€1.931
Each (In a Tube of 45)
units
1A - Buck Controller, Inverting - 4 V 40 V Fixed Through Hole - 1 5 TO-220 Yes -
RS Stock No. 146-5628
Mfr. Part No.LNK304GN
€0.655
Each (In a Tube of 50)
units
170mA 700 V Boost, Buck, Flyback -0.3 V 85 V ac 265 V ac Fixed Surface Mount - 1 8 SMDB - -
RS Stock No. 121-8927
Mfr. Part No.PTN78000WAH
€11.231
Each (In a Tube of 56)
units
1.5A - Buck Controller - - - - Through Hole - 1 5 DIP Module Yes ±10
RS Stock No. 545-7811
Mfr. Part No.PTN78000WAH
€11.87
Each
units
1.5A - Buck Controller - - - - Through Hole - 1 5 DIP Module Yes ±10
RS Stock No. 533-3181
Mfr. Part No.LM2576HVT-ADJ/NOPB
€6.04
Each
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. 920-3508
Mfr. Part No.LM2576HVT-ADJ/NOPB
€5.197
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. 920-3655
Mfr. Part No.LM2674M-5.0/NOPB
€3.385
Each (In a Tube of 95)
units
500mA - Buck Controller - 8 V 40 V Fixed Surface Mount - 1 8 SOIC Yes -
RS Stock No. 533-4954
Mfr. Part No.LM2674M-5.0/NOPB
€3.98
Each
units
500mA - Buck Controller - 8 V 40 V Fixed Surface Mount - 1 8 SOIC Yes -
RS Stock No. 841-7522
Mfr. Part No.MCP16301HT-E/CH
BrandMicrochip
€1.007
Each (In a Pack of 10)
units
600mA 15 V Step Down 2 V 4.7 V 36 V Adjustable Surface Mount - 1 6 SOT-23 Yes 0.1 %/V
RS Stock No. 165-4042
Mfr. Part No.MCP16301HT-E/CH
BrandMicrochip
€0.74
Each (On a Reel of 3000)
units
600mA 15 V Step Down 2 V 4.7 V 36 V Adjustable Surface Mount - 1 6 SOT-23 Yes 0.1 %/V
RS Stock No. 786-2350
Mfr. Part No.LM2575TV-012G
€2.02
Each (In a Pack of 5)
units
1A 12 V Buck Controller - 4.75 V 40 V Fixed Through Hole - 1 5 TO-220 Yes -
RS Stock No. 162-9816
Mfr. Part No.LMR16006YDDCT
€1.744
Each (On a Reel of 250)
units
600mA 65 V Step Down -0.3 V 4 V 60 V Adjustable Surface Mount - 1 6 SOT-23 Yes -
RS Stock No. 639-4339
Mfr. Part No.LM5005MH/NOPB
€4.15
Each
units
2.5A - Buck Controller, Inverting - 7 V 75 V Adjustable Surface Mount - 1 20 TSSOP Yes -