400-V to 690-V AC Input, 50-W Flyback Isolated Power Supply Reference Design for Motor Drives


Design files


This reference design provides isolated +24V (45W), ±16 V (4.5W), and +6V (0.5W) outputs to power the control electronics in variable speed drives.  The power supply can be either powered directly from 3-phase AC mains (380Vac to 690Vac) or can be powered from the DC-link voltage (400Vdc to 1200Vdc).  This design uses a quasi-resonant flyback topology and is rated for 50-Watt total output power.  The line and load regulation of the power supply is designed to be within 5% using primary-side regulation (eliminating costly feedback components). The power supply is designed to meet the clearance, creepage, and isolation test voltages as per IEC61800-5 requirements.

  • Versatile input: can be either 400V-1200V DC or 380V-690V AC
  • <5% line and load regulation
  • Protection against input UV/OV, output overload, short-circuit and loss of feedback
  • Low-cost solution by implementing primary-side regulation (eliminates feedback loop) and use of 1000V rated MOSFETSs
  • Quasi-resonant mode controller improves EMI performance
  • Designed to comply to IEC 61800-5
Output voltage options TIDA-00173.1
Vin (Min) (V) 400
Vin (Max) (V) 1200
Vout (Nom) (V) 24
Iout (Max) (A) 2
Output Power (W) 48
Isolated/Non-Isolated Isolated
Input Type DC
Topology Flyback- Quasi Resonant
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDU412B.PDF (6181 K)

Reference design overview and verified performance test data

TIDRB35A.PDF (261 K)

Detailed schematic diagram for design layout and components


Complete listing of design components, reference designators, and manufacturers/part numbers

TIDRB37A.ZIP (156 K)

Detailed overview of design layout for component placement

TIDRB38A.ZIP (288 K)

Detailed overview of design layout for component placement

TIDC688A.ZIP (2246 K)

Design file that contains information on physical board layer of design PCB

TIDRB39A.ZIP (348 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Flyback controllers

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Supervisor & reset ICs

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Technical documentation

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Type Title Date
* Design guide 400- to 690-V AC Input 50-W Flyback Isolated Power Supply for Motor Drives (Rev. B) May 01, 2019

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