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. 545-5045
Mfr. Part No.LT1076CT#PBF
HK$73.70
Each
units
10A 50 V Buck Controller 2.5 V 7.3 V 45 V Adjustable Through Hole - 1 5 TO-220 Yes 0.02 %/V
RS Stock No. 787-0017
Mfr. Part No.LTM8031EV#PBF
HK$209.69
Each
units
1A 10 V Buck Controller 0.8 V 3.6 V 36 V Adjustable Surface Mount - 1 71 LGA Yes 0.1 %
RS Stock No. 822-5806
Mfr. Part No.LTM8052AEV#PBF
HK$277.56
Each
units
5A 24 V Step Down 1.2 V 6 V 36 V Adjustable Surface Mount - 1 81 LGA - 0.1 %
RS Stock No. 545-6638
Mfr. Part No.LT1376CN8-5#PBF
HK$75.96
Each
units
1.5A - Buck Controller - 5 V 25 V Fixed Through Hole - 1 8 PDIP Yes 0.03 %/V
RS Stock No. 759-1819
Mfr. Part No.ADP2302ARDZ-R7
HK$24.89
Each
units
2A - Buck Controller - 3 V 20 V Adjustable Surface Mount ADP2302 1 8 SOIC - -
RS Stock No. 786-9998
Mfr. Part No.LTM4628IV#PBF
HK$461.50
Each
units
8A 5.5 V Buck Controller 0.6 V 4.5 V 26.5 V Adjustable Surface Mount - 2 144 LGA Yes 0.04 %/V
RS Stock No. 822-9965
Mfr. Part No.LT8611EUDD#PBF
HK$82.40
Each
units
1A 5 V Step Down 0.97 V 3.4 V 42 V Adjustable Surface Mount - 1 24 QFN Yes 0.02 %/V
RS Stock No. 159-7700
Mfr. Part No.ADP2302ARDZ-R7
HK$12.815
Each (On a Reel of 1000)
units
- - - - - - - Surface Mount - - 8 SOIC - -
RS Stock No. 851-4591
Mfr. Part No.LTM8023EY#PBF
HK$179.50
Each
units
2A 10 V Step Down 0.8 V 3.6 V 36 V Adjustable Surface Mount - 1 50 BGA Yes 0.1 %
RS Stock No. 802-3837
Mfr. Part No.ADP5023ACPZ-R2
HK$43.89
Each (On a Tape of 2)
units
800mA 3.8 V Buck Controller 0.8 V 2.3 V 5.5 V Adjustable Surface Mount - 3 24 LFCSP WQ Yes -0.05 %/V
RS Stock No. 711-2541
Mfr. Part No.LTM4619EV#PBF
HK$353.00
Each
units
4A 5 V Buck Controller 0.8 V 4.5 V 26.5 V Adjustable Surface Mount - 2 144 LGA Yes 0.3 %
RS Stock No. 545-5023
Mfr. Part No.LT1074CT#PBF
HK$109.54
Each
units
10A 50 V Buck Controller 2.5 V 7.3 V 45 V Adjustable Through Hole - 1 5 TO-220 Yes 0.02 %/V
RS Stock No. 779-9451
Mfr. Part No.LT1776CS8#PBF
HK$61.56
Each (In a Pack of 2)
units
1A 30 V Buck Controller 1.24 V 7.4 V 40 V - Surface Mount - 1 8 SOIC Yes 0.01 %/V
RS Stock No. 823-0004
Mfr. Part No.LTC1474IS8#PBF
HK$89.88
Each
units
100mA 12 V Step Down 1.205 V 3 V 18 V Adjustable Surface Mount - 1 8 SOIC Yes 20 mV
RS Stock No. 822-5695
Mfr. Part No.LT1767EMS8-5#PBF
HK$63.86
Each
units
1.5A 5 V Step Down - 3 V 25 V Fixed Surface Mount - 1 8 MSOP Yes -
RS Stock No. 786-9682
Mfr. Part No.LT3990IMSE#PBF
HK$62.74
Each
units
350mA 3.366 V Buck Controller 3.233 V 4.2 V 62 V Adjustable Surface Mount - 1 16 MSOP Yes 0.01 %/V
RS Stock No. 151-3326
Mfr. Part No.LT8620EUDD#PBF
HK$79.65
Each
units
2A 5 V Step Down 0.97 V 3.4 V 65 V Adjustable Surface Mount - 1 24 QFN Yes 0.02 %/V
RS Stock No. 506-0401
Mfr. Part No.LT1767EMS8#PBF
HK$63.86
Each
units
1.5A - Buck Controller - 3 V 25 V Adjustable Surface Mount - 1 8 MSOP Yes -
RS Stock No. 787-0001
Mfr. Part No.LTM8021IV#PBF
HK$135.83
Each
units
500mA 5 V Buck Controller 0.8 V 3 V 36 V Adjustable Surface Mount - 1 35 LGA Yes 0.5 %
RS Stock No. 901-3266
Mfr. Part No.LT8611IUDD#PBF
HK$90.15
Each
units
2.5A 5 V Step Down - 3.4 V 42 V Adjustable Surface Mount - 1 24 QFN Yes 0.025 %/V