Dual 15-V, 120-mA isolated bias power supply reference design using buck and push-pull converters


Design files


This isolated power supply provides dual +15-V outputs at 120 mA each. This power supply is designed for biasing a MOSFET-based power stage that generates excitation for a separately excited synchronous motor (SSM). This design uses a combination of the LMR50410-Q1 buck pre-regulator and the SN6505-Q1 open-loop transformer driver with spread-spectrum modulation. The wide-input voltage range and flexibility make this a versatile design for wide range of applications where isolated power is necessary. This internal reference design is an alternative to the PMP22760 which uses a single-chip solution based on LM5180-Q1.

  • Cost sensitive
  • Small form-factor
  • Low primary-to-secondary capacitance
  • Scalable for a wide range of applications
  • Catalog parts, including the transformer
Output voltage options PMP22992.1 PMP22992.2 PMP22992.3
Vin (Min) (V) 6 6 6
Vin (Max) (V) 36 36 36
Vout (Nom) (V) 15 15 5
Iout (Max) (A) .12 .12 .8
Output Power (W) 1.8 1.8 4
Isolated/Non-Isolated Isolated Isolated Non-Isolated
Input Type DC DC DC
Topology Forward- Push Pull Forward- Push Pull Buck- Integrated Switch
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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.

TIDT240.PDF (1166 K)

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

TIDM936.PDF (152 K)

Detailed schematic diagram for design layout and components

TIDM937.PDF (143 K)

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

TIDM938.ZIP (88 K)

Detailed overview of design layout for component placement

TIDM940.ZIP (93 K)

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

TIDCG24.ZIP (90 K)

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

TIDM939.ZIP (123 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

AC/DC & DC/DC converters (integrated FET)

LMR50410-Q1Automotive qualified SIMPLE SWITCHER 4-V to 36-V, 1-A synchronous step-down converter

Data sheet: PDF | HTML
Transformer drivers

SN6505A-Q1Automotive, low-noise, 1-A, 160-kHz transformer driver with soft start for isolated power supplies

Data sheet: PDF

Technical documentation

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Type Title Date
* Test report Dual 15-V, 120-mA Iso. Bias Power Supply Ref. Des. Using Buck & Push-Pull Conv. PDF | HTML Oct. 11, 2021
Product overview Isolated Power Topologies for PLC I/O Modules and Other Low-Power Applications PDF | HTML Nov. 09, 2022

Related design resources

Reference designs

PMP22760 Dual-output bias power supply reference design for inverter and motor drive applications

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