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. 463-050
Mfr. Part No.LM2576T-ADJG
HK$20.242
Each (In a Pack of 5)
units
3A 37 V Buck Controller, Inverting 1.23 V 7 V 40 V Adjustable Through Hole - 1 5 TO-220 Yes -
RS Stock No. 163-2400
Mfr. Part No.LM2575T-5G
HK$16.349
Each (In a Tube of 50)
units
1A 5.25 V Buck Controller 4.75 V 4.75 V 40 V Fixed Through Hole - 1 5 TO-220 Yes -
RS Stock No. 689-9932
Mfr. Part No.LM2575T-5G
HK$19.60
Each
units
1A 5.25 V Buck Controller 4.75 V 4.75 V 40 V Fixed Through Hole - 1 5 TO-220 Yes -
RS Stock No. 100-7567
Mfr. Part No.LM2576T-ADJG
HK$19.26
Each (In a Tube of 50)
units
3A 37 V Buck Controller, Inverting 1.23 V 7 V 40 V Adjustable Through Hole - 1 5 TO-220 Yes -
RS Stock No. 786-2369
Mfr. Part No.LM2576D2T-ADJR4G
HK$21.924
Each (In a Pack of 5)
units
3A 37 V Buck Controller 1.23 V - 40 V Adjustable Surface Mount - 1 5 D2PAK Yes -
RS Stock No. 808-0067
Mfr. Part No.LM2576D2T-005G
HK$17.703
Each (In a Pack of 10)
units
3A 5.25 V Buck Controller 4.75 V 8 V 40 V Adjustable Surface Mount - 1 5 D2PAK Yes -
RS Stock No. 786-2397
Mfr. Part No.LM2596DSADJR4G
HK$21.294
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. 121-6369
Mfr. Part No.LM2596DSADJR4G
HK$9.342
Each (On a Reel of 800)
units
3A 37 V Buck Controller 1.23 V 4.5 V 40 V Adjustable Surface Mount - 1 5 D2PAK Yes -
RS Stock No. 516-5657
Mfr. Part No.LM2575T-ADJG
HK$19.03
Each
units
1A 37 V Buck Controller, Inverting 1.23 V 4.75 V 40 V Adjustable Through Hole - 1 5 TO-220 Yes -
RS Stock No. 121-6364
Mfr. Part No.LM2576D2T-ADJR4G
HK$12.306
Each (On a Reel of 800)
units
3A 37 V Buck Controller 1.23 V - 40 V Adjustable Surface Mount - 1 5 D2PAK Yes -
RS Stock No. 163-2401
Mfr. Part No.LM2575T-ADJG
HK$16.212
Each (In a Tube of 50)
units
1A 37 V Buck Controller, Inverting 1.23 V 4.75 V 40 V Adjustable Through Hole - 1 5 TO-220 Yes -
RS Stock No. 163-0438
Mfr. Part No.LM2576D2T-005G
HK$20.843
Each (In a Tube of 50)
units
3A 5.25 V Buck Controller 4.75 V 8 V 40 V Adjustable Surface Mount - 1 5 D2PAK Yes -
RS Stock No. 791-9689
Mfr. Part No.NCP1595AMNR2G
HK$6.901
Each (On a Tape of 10)
units
1.5A 3.3 V Buck Controller 0.8 V 4 V 5.5 V Adjustable Surface Mount - 1 6 DFN Yes 0.06 %/V
RS Stock No. 786-2350
Mfr. Part No.LM2575TV-012G
HK$22.732
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. 170-3385
Mfr. Part No.NCP3230MNTXG
HK$13.209
Each (On a Reel of 2500)
units
140µA 5.45 V Synchronous Buck Controller 4.9 V 4.5 V 18 V Adjustable Surface Mount - 1 40 QFN - -
RS Stock No. 786-2391
Mfr. Part No.LM2596TVADJG
HK$20.938
Each (In a Pack of 5)
units
3A 37 V Buck Controller 1.23 V 4.5 V 40 V Adjustable Through Hole - 1 5 TO-220 Yes -
RS Stock No. 786-2379
Mfr. Part No.LM2576TV-012G
HK$19.498
Each (In a Pack of 5)
units
3A 12 V Buck Controller - - 40 V Fixed Through Hole - 1 5 TO-220 Yes -
RS Stock No. 161-2613
Mfr. Part No.NCP1532MUAATXG
HK$5.717
Each (On a Reel of 3000)
units
1.6A 3.3 V Step Down 0.9 V 2.7 V 5.5 V Adjustable Surface Mount - 1 10 UDFN Yes 0.05 %
RS Stock No. 121-9882
Mfr. Part No.NCP1599MNTWG
HK$5.576
Each (On a Reel of 3000)
units
3A 3.3 V Buck Controller 0.8 V 3 V 5.5 V Adjustable Surface Mount - 1 6 DFN Yes 0.03 %/V
RS Stock No. 791-9677
Mfr. Part No.NCP1587DR2G
HK$5.469
Each (On a Tape of 10)
units
120µA 1.6 V Buck Controller 0.8 V 4.5 V 13.2 V Adjustable Surface Mount - 1 8 SOIC Yes -