access icon free Adaptive line voltage compensation scheme for a source-driving controlled AC–DC LED driver

A primary-side controlled high-precision constant current AC–DC LED driver, based on source-driving control scheme, is designed for low-power LED-lighting applications in this study. The ratio between demagnetisation time T Demag and switching period T S and the primary peak current are remained constant by the proposed control IC, obtaining constant current output. Meanwhile, an adaptive line voltage compensation circuit, integrated in the primary peak current controller, is proposed based on source-driving control scheme. A compensation current proportional to line voltage is injected to the primary-side current sampling pin CS, thus making the turn-off bandgap reference of primary peak current under high-line voltage lower than that under low-line voltage. As a consequence, overshoot phenomena of primary peak current can be avoided, and the line regulation as well as the precision of output current can be improved. The proposed control IC has been fabricated in TSMC 0.35 μm 5 V/650 V CMOS/LDMOS process. Experimental results of a 5 W prototype show that the output current is kept stable at ∼250 mA, and the line regulation is within ±0.5% in a wide range of universal-input ac voltage from 85 to 264 V, and that >80% efficiency is obtained under heavy LED loads.

Inspec keywords: CMOS integrated circuits; electric current control; compensation; driver circuits

Other keywords: turn-off bandgap reference; size 0.35 mum; primary peak current; voltage 650 V; low-power LED-lighting application; TSMC; peak current controller; demagnetisation time; control IC; source-driving controlled AC–DC LED driver; source-driving control scheme; LDMOS process; power 5 W; line regulation; primary-side current sampling pin CS; CMOS process; adaptive line voltage compensation scheme; voltage 5 V; primary-side controlled high-precision constant current

Subjects: Power electronics, supply and supervisory circuits; Current control; CMOS integrated circuits

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http://iet.metastore.ingenta.com/content/journals/10.1049/iet-cds.2016.0171
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