A 93.3% peak-efficiency self-resonant hybrid-switched-capacitor LED driver in 0.18-μm CMOS technology

Juan C. Castellanos, Mert Turhan, Eugenio Cantatore

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)
2 Downloads (Pure)


This paper presents an integrated light-emitting diode (LED) driver based on a self-resonant hybrid-switched-capacitor converter (H-SCC) operating in the megahertz range. An integrated zero-current detection (ZCD) circuit is designed to enable self-resonant operation and zero-current switching. A self-resonant timer is proposed to set the switching frequency to resonance automatically, accommodating for variations in the LED voltage, output current, inductor value, and/or parasitic components, and improving the converter efficiency at light loads without the need for an accurate clock with variable frequency. A ZCD threshold control is also proposed to enable continuous conduction mode and improve efficiency at large currents. The design of high-speed integrated current sensors to measure the inductor current in the H-SCC is also presented. Capacitors, power switches, ZCD, current monitors, and the control circuitry of the LED driver are integrated on-chip in a low-cost, 5-V, 0.18-μm bulk CMOS technology. The proposed driver was measured using inductor values between 36 and 470 nH. It achieves a peak efficiency of 93.3% and an efficiency of 83.1% at the nominal current. The LED driver is able to control a 700-mA LED down to less than 10% of its nominal current. The effective chip area is 7.5 mm 2, and the maximum power density is 373 mW/mm 2. To our knowledge, this LED driver can achieve efficiencies comparable to prior art LED drivers using a 6.6 × smaller inductor.

Original languageEnglish
Article number8353793
Pages (from-to)1924-1935
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Issue number7
Publication statusPublished - 1 Jul 2018


  • CMOS integrated circuit
  • light-emitting diode (LED) drivers
  • power integrated circuits
  • switching converters
  • zero-current switching (ZCD)

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