45-W high-power-density active clamp flyback with GaN reference design for server auxiliary power


Design files


This reference design is a GaN-based 45-W active-clamp flyback (ACF) targeting maximum power density. This supply is designed to provide auxiliary power in server and telecom power supply units (PSUs). The UCC28782 ACF controller and LMG2610 GaN half-bridge are used to drive a planar transformer with synchronous rectification using UCC24612. This auxiliary supply is designed to operate using the PFC bus voltage as an input, and generates an isolated 12-V output capable of supplying 3.7 A and a non-isolated 18-V output capable of supplying up to 400 mA. The main isolated 12-V output is protected by the TPS74800 ORing controller. Multiple PMP23146 units can be operated in parallel for higher power capability, and load sharing is ensured by droop compensation. The ACF topology and GaN allow this design to operate at 400 kHz and fit into the small dimensions of 30 mm x 35 mm x 12 mm, for a power density of approximately 60 W/in3.

  • 400-kHz high frequency GaN ACF design with planar transformer
  • Compact size of 30 mm x 35 mm x 12 mm) and high power density of 60W/in3
  • Parallelable for higher power capability
  • Low standby power consumption of <100 mW
  • Additional non-isolated 18-V output provided
Output voltage options PMP23146.1
Vin (Min) (V) 200
Vin (Max) (V) 410
Vout (Nom) (V) 12
Iout (Max) (A) 3.7
Output Power (W) 44.4
Isolated/Non-Isolated Isolated
Input Type DC
Topology Flyback- Active Clamp
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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.

TIDT320A.PDF (1982 K)

Test results for the reference design, including efficiency graphs, test prerequisites and more


Detailed schematic diagram for design layout and components


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


Detailed overview of design layout for component placement

TIDMBC6.ZIP (2494 K)

Files used for 3D models or 2D drawings of IC components

TIDCGD4.ZIP (2122 K)

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


PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Flyback controllers

UCC28782High-density flyback controller for active-clamp (ACF) and zero-voltage switching (ZVS) topologies

Data sheet: PDF | HTML
Gallium nitride (GaN) ICs

LMG2610650-V 170/248-mΩ GaN half-bridge for ACF with integrated driver, protection and current sense

Data sheet: PDF | HTML
General-purpose op amps

OPA170Single, 36-V, 1.2-MHz, low-power operational amplifier

Data sheet: PDF | HTML
Ideal diode/ORing controllers

LM7480-Q13-V to 65-V, automotive ideal diode controller driving back to back NFETs

Data sheet: PDF | HTML
Linear & low-dropout (LDO) regulators

TPS7A19450-mA, 40-V, low-IQ, adjustable low-dropout voltage regulator with power good & enable

Data sheet: PDF | HTML
N-channel MOSFETs

CSD17575Q330-V, N channel NexFET™ power MOSFET, single SON 3 mm x 3 mm, 3.2 mOhm

Data sheet: PDF | HTML
SR & load share controllers

UCC24612High-frequency multi-mode synchronous rectifier controller

Data sheet: PDF | HTML
Shunt voltage references

LM4040Fixed voltage, 45-µA, precision micropower shunt voltage reference

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
Test report 45-W High-Power-Density Active Clamp Flyback W/ GaN Ref. Des. - Server Aux Power (Rev. A) PDF | HTML Jul. 30, 2023

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