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Lone Star Step Down 24V To 12V Converter

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Part# 11-03309
MFR Model# LS03-05001-B


Lone Star Aviation’s FAA TSO approved DC-DC down converter is the first choice among OEMs and dealers for a high reliability power supply. This third generation converter was designed to operate as a STEP UP or STEP DOWN power supply. The main converter output is for 28VDC to 13.8VDC to a maximum of 10/12P Amps which operates 13.8 vdc equipment in a 28 volt aircraft.

Additional outputs for the STEP DOWN are 5, 7.5, 9, 13.8, 16, 19, 24, 28 vdc. The STEP UP is an option and special order for 14 volts to 5, 7.5, 9, 13.8, 16, 19, 24, 28 vdc. Designed with our latest dc power module operates at 96% efficiency, multiple output voltages and OV, OC, OT, SC, RP protections. LS03-05001-B was tested under RTCA DO160G environmental testing.

The connector kit – LS03-05026-1, is required and sold separately.

    Specification Overview
  • Input Voltage: 14/28 vdc
  • Input Current: 2-15 Amps
  • Output Voltage: 5, 7.5, 9, 13.8, 16, 19, 24, 28 vdc
  • Output Current: 4A/5A Peak, 7A/8A Peak, or 10/12A Peak
  • *Reference ‘Specifications LS03-05001-B Big Down Converter’ in Downloads
  • Ripple: 580mV
  • Protections: OC, OV, OT, SC, RP
  • RTCA DO160G Tested
  • FAA TSO Approved
California Prop 65 Warning Symbol

WARNING: Cancer and Reproductive Harm -


Great product! Did just what I needed it to do. Easy to install.

Seth T
November 10, 2023

the photo on the website does not reflect the updated item that you will receive. You need to purchase the connector as the updated version of the converter requires it and has no possibilities for ring terminals.

Vintech A Verified Purchase


July 28, 2022


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: What the Lone Star Step Down 24V to 12V Converter's current rating?

Per the manufacturer, Input: 27.5 Volts, Input: 5.6 Amps, Output: 14.06 Volts, Output 10 Amps.

Q: Is the output adjustable? If so, what range?

No, the voltage is set at 12V and is not adjustable.

Q: Is the Lone Star Step Down 24v to 12v TSOed?

Yes, it is.

Q: Does this converter have back voltage protection?

Yes. The LS03-05001-A dc converter has over voltage protection.

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