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


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

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(Output Voltage 1)
Vin (Min) (V)400
Vin (Max) (V)1200
Vout (Nom) (V)24
Iout (Max) (A)2
Output Power (W)48
Input TypeDC
TopologyFlyback- Quasi Resonant

TI Devices (2)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
LMS33460  Ultra-low power, space-saving 3-V undervoltage detector  Power management  Sample & Buy Not Available
UCC28711  Constant-voltage, constant-current PWM with PSR, valley switching, NTC option, and 0-mV cable comp.  Offline & isolated DC/DC controllers & converters  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
LMS33460 Download Download
UCC28711 Download

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Technical documentation

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User guides (1)
Title Type Size (KB) Date
PDF 6081 01 May 2019
Design files (6)
Title Type Size (KB) Date
PDF 261 01 May 2019
ZIP 348 01 May 2019
ZIP 2246 01 May 2019
ZIP 288 01 May 2019
PDF 62 01 May 2019
ZIP 156 01 May 2019

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