AC-DC auxiliary power supplies

Infineon's wide and scalable portfolio delivering advanced integration with ZVS, X-Cap discharge and Zero Crossing Detection capabilities

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Overview

Elevate system robustness with Infineon's auxiliary power supplies solutions. Our scalable CoolSET™ portfolio provides main or standby supply for critical systems across home appliances, servers, data centers and industrial & consumer applications. Achieve maximum stability & efficiency with high-performance CoolSET™, supporting isolated & non-isolated topologies up to 100W.

Benefits

  • High efficiency
  • Integrated SR controller
  • Low component count
  • Supports wide input voltage
  • Supports flyback and buck topology
  • Range of ZVS, FF and QR operation

Block diagram

About

Why is auxiliary power supply critical in modern applications?

An auxiliary SMPS is a dedicated power source that operates independently from the main supply to support functions such as standby operation, gate driver bias, MCU and sensor powering, and communication modules. Power ratings for these auxiliary supplies typically range from a few watts to a few tens of watts, and the output can be either isolated or non-isolated.

To ensure good performance, engineers must select a power topology which includes isolated flyback, non-isolated flyback, or non-isolated buck that best meets the efficiency, size, safety, and cost requirements of the target system. Isolated auxiliary power supply designs are commonly required when output rails must be electrically separated from the AC input, while non-isolated auxiliary supply configurations are well-suited for applications where a shared ground reference is acceptable.

What are the key topologies used in AC-DC auxiliary power supplies?

Common AC-DC topologies include Flyback, Buck, Boost, PFC & LLC resonant converters. Each topology offers distinct advantages depending on power range, isolation requirements & efficiency targets, allowing designers to select the most suitable approach for their specific application.

Infineon’s CoolSET™ portfolio include isolated and non-isolated Flyback and non-isolated buck topology. With increased reliability and outstanding performance, CoolSET™  is designed to offer additional protection to increase system robustness in your auxiliary power supply. 

CoolSET™ Flyback ICs
AC-DC PFC controllers
Infineon's scalable solution across multiple power ranges

The CoolSET™ SiP portfolio offers high forward integration with an option of 800V or  950V avalanche rugged CoolMOS™ P7 or a 800V CoolSiC™, a Zero Voltage Switching (ZVS) primary controller, and secondary SR controller with CT Link technology for isolated communication and Zero Voltage Switching (ZVS) enabled to deliver exceptional performance. The portfolio can deliver an output power of up-to 136W.

The CoolSET™ Switch portfolio includes the Fixed Frequency (FF) and Quasi Resonant (QR) range of products supporting output power up to 43W. Integrated with 700 V, 800 V, 950 V avalanche rugged CoolMOS™ P7 family, the CoolSET™ Switch product range is available in both through-hole and SMD packages.

The CoolSET™ PWM portfolio also includes the Fixed Frequency (FF) and Quasi Resonant (QR) range of products. The PWM controller can be paired with an external up to 1200V Switch or a 1700V CoolSiC™ to deliver output power up to 114W.

CoolSET™ SiP
CoolSET™ Switch
CoolSET™ PWM
PowerEsim design software

Simulate, optimize, export. Complete your design by running an electrical simulation, export to your most used CAD tools, print a design PDF report, or start a new design. Key capabilities include:

  • Thermal analysis and component loss analysis
  • Feedback loop and MTBF analysis
  • EMI and Monte Carlo simulation
  • Transformer winding design
  • Design verification test (DVT) report generation

Experience it firsthand and click the link below to start your design.

Frequently Asked Questions

Q: What is the difference between an isolated and a non-isolated auxiliary power supply?

An isolated auxiliary power supply uses a transformer to provide electrical separation between the input and output, which is required when output rails must be kept independent from the AC input for safety or regulatory reasons. A non-isolated auxiliary supply shares a common ground reference with the input and is typically used in applications such as outdoor air-conditioning units, where isolation is not required.

Q: What output power levels does Infineon's CoolSET™ support for auxiliary SMPS designs?

Infineon's CoolSET™ portfolio supports flyback auxiliary power supply designs from a few watts up to 136 W, and non-isolated buck designs up to 700 mA output current. Evaluation and reference boards are available across this power range to accelerate time to market.

Q: When should I choose quasi-resonant switching over fixed frequency for an auxiliary power supply?

Quasi-resonant (QR) switching is better suited for designs prioritizing higher light-load efficiency and lower EMI through valley switching, particularly in isolated flyback topologies. Fixed frequency (FF) operation is well-suited when precise timing control, CCM operation, or compatibility with simpler EMI filtering is required, and it additionally supports non-isolated buck and flyback topologies.

Why is auxiliary power supply critical in modern applications?

An auxiliary SMPS is a dedicated power source that operates independently from the main supply to support functions such as standby operation, gate driver bias, MCU and sensor powering, and communication modules. Power ratings for these auxiliary supplies typically range from a few watts to a few tens of watts, and the output can be either isolated or non-isolated.

To ensure good performance, engineers must select a power topology which includes isolated flyback, non-isolated flyback, or non-isolated buck that best meets the efficiency, size, safety, and cost requirements of the target system. Isolated auxiliary power supply designs are commonly required when output rails must be electrically separated from the AC input, while non-isolated auxiliary supply configurations are well-suited for applications where a shared ground reference is acceptable.

What are the key topologies used in AC-DC auxiliary power supplies?

Common AC-DC topologies include Flyback, Buck, Boost, PFC & LLC resonant converters. Each topology offers distinct advantages depending on power range, isolation requirements & efficiency targets, allowing designers to select the most suitable approach for their specific application.

Infineon’s CoolSET™ portfolio include isolated and non-isolated Flyback and non-isolated buck topology. With increased reliability and outstanding performance, CoolSET™  is designed to offer additional protection to increase system robustness in your auxiliary power supply. 

CoolSET™ Flyback ICs
AC-DC PFC controllers
Infineon's scalable solution across multiple power ranges

The CoolSET™ SiP portfolio offers high forward integration with an option of 800V or  950V avalanche rugged CoolMOS™ P7 or a 800V CoolSiC™, a Zero Voltage Switching (ZVS) primary controller, and secondary SR controller with CT Link technology for isolated communication and Zero Voltage Switching (ZVS) enabled to deliver exceptional performance. The portfolio can deliver an output power of up-to 136W.

The CoolSET™ Switch portfolio includes the Fixed Frequency (FF) and Quasi Resonant (QR) range of products supporting output power up to 43W. Integrated with 700 V, 800 V, 950 V avalanche rugged CoolMOS™ P7 family, the CoolSET™ Switch product range is available in both through-hole and SMD packages.

The CoolSET™ PWM portfolio also includes the Fixed Frequency (FF) and Quasi Resonant (QR) range of products. The PWM controller can be paired with an external up to 1200V Switch or a 1700V CoolSiC™ to deliver output power up to 114W.

CoolSET™ SiP
CoolSET™ Switch
CoolSET™ PWM
PowerEsim design software

Simulate, optimize, export. Complete your design by running an electrical simulation, export to your most used CAD tools, print a design PDF report, or start a new design. Key capabilities include:

  • Thermal analysis and component loss analysis
  • Feedback loop and MTBF analysis
  • EMI and Monte Carlo simulation
  • Transformer winding design
  • Design verification test (DVT) report generation

Experience it firsthand and click the link below to start your design.

Frequently Asked Questions

Q: What is the difference between an isolated and a non-isolated auxiliary power supply?

An isolated auxiliary power supply uses a transformer to provide electrical separation between the input and output, which is required when output rails must be kept independent from the AC input for safety or regulatory reasons. A non-isolated auxiliary supply shares a common ground reference with the input and is typically used in applications such as outdoor air-conditioning units, where isolation is not required.

Q: What output power levels does Infineon's CoolSET™ support for auxiliary SMPS designs?

Infineon's CoolSET™ portfolio supports flyback auxiliary power supply designs from a few watts up to 136 W, and non-isolated buck designs up to 700 mA output current. Evaluation and reference boards are available across this power range to accelerate time to market.

Q: When should I choose quasi-resonant switching over fixed frequency for an auxiliary power supply?

Quasi-resonant (QR) switching is better suited for designs prioritizing higher light-load efficiency and lower EMI through valley switching, particularly in isolated flyback topologies. Fixed frequency (FF) operation is well-suited when precise timing control, CCM operation, or compatibility with simpler EMI filtering is required, and it additionally supports non-isolated buck and flyback topologies.

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