Experimental assessment of active-resistive circuit implementation in LED drivers for reducing inrush current and enhancing operational life of products

The paper addresses the issue of inrush current limitation in LED drivers, which is an important task for modern LED systems. The focus is on the application of an adapted classical inrush current limiting scheme using a time relay and a limiting resistor for use in LED drivers. The proposed circuit includes a transformer, a diode bridge, a voltage regulator, capacitors, an NE555P timer IC, and a relay for controlling resistor R2. The paper also provides a literature review of modern inrush current limiting methods, such as thermistors and MOSFET circuits, with an analysis of their advantages and disadvantages. For the study, five models of LED drivers with a power rating of 36 W and a voltage of 12 V were selected. Current values were measured using the FNIRSI-2C23T oscilloscope, which allowed the changes in inrush current to be recorded. Measurement errors due to the oscilloscope, measurement probe, and current-sensing shunt were evaluated. The experimental results demonstrated a reduction in inrush current when using the proposed circuit. The calculations for determining the limiting resistor's nominal value and assessing power losses took into account the necessary parameters, confirming the correctness of the circuit choice. Possible ways to improve the circuit were also discussed, including the use of transformerless electromagnetic relay control to further optimize the device.

1. Tiflov A. V. Modern methods of limiting inrush currents in power sources // Power electronics. 2019. No. 4. pp. 40-43.

2. Nikiforov S., Arkhipov A. Regulator of the phase of the transient process in alternating voltage circuits for measuring starting and starting currents of electrical devices // Semiconductor lighting engineering. 2020. No. 5.

3. Korotkov S. M., Lukin A. V. Power supplies for LED lighting // Practical power electronics. Moscow: MMP-Irbis, 2012, pp. 3-9.

4. Saprykin A., Uelin V., Volgaraev K. Starting and/or starting current? // Semiconductor lighting technology. 2020. No. 3. pp. 26-29.

5. Roberts S. Causes and solution of the inrush current problem: a short guide // Power Electronics. - 2021. - No. 2. - pp. 64-67.

6. Krutikov K. K., Rozhkov V. V., Leonov I. E., Belousov D. V., Romanov D. A., Rudnyakov K. A. The current state and solution of the problem of soft start of switching power supplies // Practical power electronics. - 2018. - No. 4. - pp. 42-46.

7. Abramov A., Bogdanov A., Danilko A., Dmitriev P., Karev A., Stepanov A. Electrical characteristics of OP with LED light sources when switched on and requirements for protection devices of the power supply network // Semiconductor lighting engineering. - 2020. - No. 2. - pp. 12-15.

8. Mathiou S., Lambert H., Jammet P. Impact of LED Lighting on Electrical Networks // Schneider Electric White Paper. - 10/15/2014. - Article 1.

9. Ways to Limit the Inrush Current of LED Devices in Order to Increase the Service Life of Products by V.R. Ivanova, R.R. Safina // South Siberian Scientific Bulletin. – 2025. – No. 4. – pp. 53-57.

10. Charging the capacitor // NRU MEPhI URL: https://online.mephi.ru/courses/physics/electricity/data/course/4/4.4.html (date of reference: 07/15/2025).

11. Mack R. Switching power supplies. Theoretical foundations of design and a guide to practical application/ Translated from English. — M.: Publishing house "Dodeka-XXI", 2008. — 272 p.: ill. (Series "Power electronics").

12. Zabrodin Y. S. Industrial electronics. - ER-277 ed. - 09/24/81: Higher School, 1982. - 489 p.

13. Sze S. M. Physics of Semiconductor devices. - 2nd ed. - New Jersey: Wiley-Interscience, 1981. - 456 p.

14. IOTA Engineering Qualifying Emergency Lighting to NEMA 410 Standards // TECH BRIEF Emergency Lighting and Inrush Protection. - 2018. - №REV 040918.

15. LED Driver Inrush Current and MCB Quantity // uPowerTek URL: https://www.upowertek.com (date of request: 02/15/2025).

16. How to measure current with an oscilloscope: choosing the optimal method // supereyes. URL: https://supereyes.ru/ (accessed: 13.10.2025).

17. TDK Corporation. NTC Thermistors for Inrush Current Limiting: Technical Guide and Application Manual. Tokyo: TDK Electronics AG, 2023. 36 p. URL: https://www.tdk-electronics.tdk.com/download/532341/4b8e136e9f1e7c35b18e25c45297697c/pdf-inrush-currentlimiting-ntc-thermistors.pdf (accessed: 20.01.2026).

18. Infineon Technologies AG. PROFET+2 12V: Smart High-Side Power Switches for Automotive and Industrial Applications. Datasheet. Munich: Infineon Technologies, 2024. 48 p. URL: https://www.infineon.com/dgdl/Infineon-PROFET-2-12V-DS-v02_00-EN.pdf (accessed: 20.01.2026).

19. Omron Electronics LLC. G2RL Series Power PCB Relays: Technical Specifications and Application Guide. Schaumburg: Omron Corporation, 2023. 45 p. URL: https://www.omron.com/ecb/products/pdf/RELAY_POWER_PCB_G2RL.pdf (accessed: 20.01.2026).

20. Vishay Intertechnology Inc. SMD Inrush Current Limiting PTC Thermistors: Design Guide for LED Driver Applications. Malvern: Vishay, 2024. 28 p. URL: https://www.vishay.com/docs/29074/smdinrush.pdf (accessed: 20.01.2026).

21. STMicroelectronics. LED Driver ICs with Integrated Inrush Current Limiting: Application Note AN5321. Geneva: STMicroelectronics, 2023. 32 p. URL: https://www.st.com/resource/en/application_note/an5321-led-driver-ics-with-integrated-inrushcurrent-limiting-stmicroelectronics.pdf (accessed: 20.01.2026).

22. Investigation of ways to limit the inrush current of led devices in order to increase the operational life of products / V.R. Ivanova, R.R. Safin // South Siberian Scientific Bulletin. – 2025. – No. 4. – pp. 53-57.