Modern auto industry is ubiquitously deploying electronic systems for several applications like control, infotainment and security among others in the vehicles. Automotive infotainment is a key segment for the growth of automotive electronics as the vehicles, both light and heavy, require radio, video, navigation-assistance and telematics systems for both entertainment and networking. Like any battery-operated systems, the automotive infotainment systems are required to provide high efficiency. One major constituent of in-vehicle infotainment being the radio, improving the overall efficiency of a car radio system is emphasized by the industry. In the state-of-the-art, the automotive audio amplifiers severely lack efficiency offering <40% in the mute condition. This research targets to improve the overall efficiency of an audio amplifier in a car radio by power supplying efficiently. A Single Inductor Multiple Output dc-dc converter is explored as a supply voltage generator for an automotive audio amplifier in a car radio. The presence of line and load fluctuations, together with wide range of operating temperatures, in the automotive environment pose major challenge to the voltage regulation. A systematic feasibility study and analysis of specifications brought out the equivalence between the target SIMO converter and a non-inverting buck-boost SISO converter. Based on the equivalence, equilibrium and small signal models for the SIMO converter are developed. A voltage-mode, error-based controller is designed to control the dynamics of the converter. A novel power switching stage is conceived to generate the supplies required in a multi-channel class-D power amplifier. The switch configuration is critical due the absence of a well-defined reference to one of the regulated outputs and the effect of package parasitics at high switching frequencies. The converter is charged synchronously and discharged quasi-synchronously to the loads. The switches are configured and driven optimally based on extensive simulations in the presence of package models to suppress the switching noise. In order to reduce the EM interference in the AM band of interest, the SIMO converter is switched at permissible high frequencies based on the EMI mask. The automotive-class SIMO dc-dc converter is designed and integrated with a state-of-the-art class-D audio amplifier using 110nm BCD process technology offered by STMicroelectronics. The SIMO converter provides a battery tracking boost and a ground referred buck outputs for driving the class-D power stage. A unique feature of the converter is the generation of a floating voltage across half battery to supply the DSP core of the amplifier. The converter starts-up as boost converter alone followed entering boost-assisted SIMO converter mode. The active area occupied is 2.5mm2. The switching frequency is 2-2.4MHz. The converter has a load capability to drive up to 4 channels of a class-D power stage with peak efficiency of 86% and peak output power of 2.8W. The ripple voltage on the regulated outputs is below 25mV. The SIMO converter is able to sustain the automotive battery crank and dump conditions across the battery variation range of 4.5-27V. A line regulation of 6.3-16.2mV/V and a load regulation of 0.16mV/mA are provided by the SIMO converter. In the presence of wide range of battery variations, the SIMO converter incorporates all the necessary protections circuits and under/over voltage interrupts through I2C communication.
Modern auto industry is ubiquitously deploying electronic systems for several applications like control, infotainment and security among others in the vehicles. Automotive infotainment is a key segment for the growth of automotive electronics as the vehicles, both light and heavy, require radio, video, navigation-assistance and telematics systems for both entertainment and networking. Like any battery-operated systems, the automotive infotainment systems are required to provide high efficiency. One major constituent of in-vehicle infotainment being the radio, improving the overall efficiency of a car radio system is emphasized by the industry. In the state-of-the-art, the automotive audio amplifiers severely lack efficiency offering <40% in the mute condition. This research targets to improve the overall efficiency of an audio amplifier in a car radio by power supplying efficiently. A Single Inductor Multiple Output dc-dc converter is explored as a supply voltage generator for an automotive audio amplifier in a car radio. The presence of line and load fluctuations, together with wide range of operating temperatures, in the automotive environment pose major challenge to the voltage regulation. A systematic feasibility study and analysis of specifications brought out the equivalence between the target SIMO converter and a non-inverting buck-boost SISO converter. Based on the equivalence, equilibrium and small signal models for the SIMO converter are developed. A voltage-mode, error-based controller is designed to control the dynamics of the converter. A novel power switching stage is conceived to generate the supplies required in a multi-channel class-D power amplifier. The switch configuration is critical due the absence of a well-defined reference to one of the regulated outputs and the effect of package parasitics at high switching frequencies. The converter is charged synchronously and discharged quasi-synchronously to the loads. The switches are configured and driven optimally based on extensive simulations in the presence of package models to suppress the switching noise. In order to reduce the EM interference in the AM band of interest, the SIMO converter is switched at permissible high frequencies based on the EMI mask. The automotive-class SIMO dc-dc converter is designed and integrated with a state-of-the-art class-D audio amplifier using 110nm BCD process technology offered by STMicroelectronics. The SIMO converter provides a battery tracking boost and a ground referred buck outputs for driving the class-D power stage. A unique feature of the converter is the generation of a floating voltage across half battery to supply the DSP core of the amplifier. The converter starts-up as boost converter alone followed entering boost-assisted SIMO converter mode. The active area occupied is 2.5mm2. The switching frequency is 2-2.4MHz. The converter has a load capability to drive up to 4 channels of a class-D power stage with peak efficiency of 86% and peak output power of 2.8W. The ripple voltage on the regulated outputs is below 25mV. The SIMO converter is able to sustain the automotive battery crank and dump conditions across the battery variation range of 4.5-27V. A line regulation of 6.3-16.2mV/V and a load regulation of 0.16mV/mA are provided by the SIMO converter. In the presence of wide range of battery variations, the SIMO converter incorporates all the necessary protections circuits and under/over voltage interrupts through I2C communication.
SIMO DC-DC Converter for Automotive Audio Amplifier
SALIMATH, ARUNKUMAR
2018-03-02
Abstract
Modern auto industry is ubiquitously deploying electronic systems for several applications like control, infotainment and security among others in the vehicles. Automotive infotainment is a key segment for the growth of automotive electronics as the vehicles, both light and heavy, require radio, video, navigation-assistance and telematics systems for both entertainment and networking. Like any battery-operated systems, the automotive infotainment systems are required to provide high efficiency. One major constituent of in-vehicle infotainment being the radio, improving the overall efficiency of a car radio system is emphasized by the industry. In the state-of-the-art, the automotive audio amplifiers severely lack efficiency offering <40% in the mute condition. This research targets to improve the overall efficiency of an audio amplifier in a car radio by power supplying efficiently. A Single Inductor Multiple Output dc-dc converter is explored as a supply voltage generator for an automotive audio amplifier in a car radio. The presence of line and load fluctuations, together with wide range of operating temperatures, in the automotive environment pose major challenge to the voltage regulation. A systematic feasibility study and analysis of specifications brought out the equivalence between the target SIMO converter and a non-inverting buck-boost SISO converter. Based on the equivalence, equilibrium and small signal models for the SIMO converter are developed. A voltage-mode, error-based controller is designed to control the dynamics of the converter. A novel power switching stage is conceived to generate the supplies required in a multi-channel class-D power amplifier. The switch configuration is critical due the absence of a well-defined reference to one of the regulated outputs and the effect of package parasitics at high switching frequencies. The converter is charged synchronously and discharged quasi-synchronously to the loads. The switches are configured and driven optimally based on extensive simulations in the presence of package models to suppress the switching noise. In order to reduce the EM interference in the AM band of interest, the SIMO converter is switched at permissible high frequencies based on the EMI mask. The automotive-class SIMO dc-dc converter is designed and integrated with a state-of-the-art class-D audio amplifier using 110nm BCD process technology offered by STMicroelectronics. The SIMO converter provides a battery tracking boost and a ground referred buck outputs for driving the class-D power stage. A unique feature of the converter is the generation of a floating voltage across half battery to supply the DSP core of the amplifier. The converter starts-up as boost converter alone followed entering boost-assisted SIMO converter mode. The active area occupied is 2.5mm2. The switching frequency is 2-2.4MHz. The converter has a load capability to drive up to 4 channels of a class-D power stage with peak efficiency of 86% and peak output power of 2.8W. The ripple voltage on the regulated outputs is below 25mV. The SIMO converter is able to sustain the automotive battery crank and dump conditions across the battery variation range of 4.5-27V. A line regulation of 6.3-16.2mV/V and a load regulation of 0.16mV/mA are provided by the SIMO converter. In the presence of wide range of battery variations, the SIMO converter incorporates all the necessary protections circuits and under/over voltage interrupts through I2C communication.| File | Dimensione | Formato | |
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ThesisArun.pdf
Open Access dal 03/09/2019
Descrizione: tesi di dottorato
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4.97 MB
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