Abstract
This article presents a hybrid boost converter architecture for improving the efficiency of light-emitting diode (LED) drivers used in mobile applications. By cascading a low-switching frequency time-interleaved series–parallel switched-capacitor (SC)-stage with an inductive-boost converter, we facilitate lower voltage-rated switches, thus significantly reducing the switching losses. Charge-sharing losses of the SC stage are minimized by soft-charging flying capacitors with the inductor of the boost (BST) stage. Fabricated in 180-nm bipolar CMOS DMOS (BCD) process, the prototype converter generates 30-V output voltage from a Li-ion battery source. It can provide a load current in the range of 0–100 mA with an excellent peak power efficiency of 91.15% at 30 mA, which represents a 3% improvement over the state of the art.
Highlights
R APID technological advances over the last decade have made the display module an integral part of modern portable electronic devices, such as smartphones and tablets
Switches S1 and S2 are driven by complementary pulse width modulated (PWM) signals with a duty cycle of D and (1− D) and generates an output voltage given by the following equation: VOUT
The SC-stage switching frequency is initially increased to 500 kHz, which is five times the steady-state switching frequency and reduced back to 100 kHz after CFLY,1 and CFLY,2 are charged to VOUT/2 and the output capacitor is charged to VOUT
Summary
R APID technological advances over the last decade have made the display module an integral part of modern portable electronic devices, such as smartphones and tablets. Switches S1 and S2 are driven by complementary pulse width modulated (PWM) signals with a duty cycle of D and (1− D) and generates an output voltage given by the following equation: VOUT Even though this architecture requires very few off-chip components, its efficiency is fundamentally limited by the switches’ high voltage rating. A class of switched-capacitor (SC)-based converters can generate high output voltages using devices rated lower than the output voltage [4], [5] They incur a considerable amount of charge-sharing losses at typical LED driver’s operating power levels. This article presents a high-efficiency boost converter for LED-driver applications with an input voltage range of 2.3–5 V, an output voltage range of 10–35 V, and a load range of 0–100 mA [11].
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