A fully integrated LED driver based on a current mode PWM boost DC-DC converter with constant output current is proposed. In order to suppress the inrush of current and the overshoot voltage at the start up state, a s...A fully integrated LED driver based on a current mode PWM boost DC-DC converter with constant output current is proposed. In order to suppress the inrush of current and the overshoot voltage at the start up state, a soft-start circuit is adopted. Additionally, to adjust the LED brightness without color variation over the full dimming range and achieve high efficiency, a PWM dimming circuit is presented. Furthermore, to keep the loop stability of the LED driver, an internal slope compensation network is designed to avoid the sub-harmonic oscillation when the duty cycle exceeds 50%. Finally, a UVLO circuit is adopted to improve the reliability of the LED driver against the input voltage changing. The LED driver has been fabricated with a standard 0.5/xm CMOS process, and only occupies 1.21 × 0.76 mm^2. Experimental results show that the brightness of the LED can be adjusted by an off- chip PWM signal with a wide adjusting range. The inductor current and output current increase smoothly over the whole load range. The chip is in the UVLO condition when the input voltage is below 2.18 V and has achieved about 137 μs typical start-up time.展开更多
We demonstrate the key module of comparators in GaN ICs,based on resistor-transistor logic(RTL)on E-mode wafers in this work.The fundamental inverters in the comparator consist of a p-GaN gate HEMT and a 2DEG resistor...We demonstrate the key module of comparators in GaN ICs,based on resistor-transistor logic(RTL)on E-mode wafers in this work.The fundamental inverters in the comparator consist of a p-GaN gate HEMT and a 2DEG resistor as the load.The function of the RTL comparators is finally verified by a undervoltage lockout(UVLO)circuit.The compatibility of this circuit with the current p-GaN technology paves the way for integrating logic ICs together with the power devices.展开更多
以太网供电PoE(Power Over Ethernet)是一种局域网技术,通过现有的Cat5/Cat5e/Cat6以太网电缆给IP终端设备(如IP电话机、无线局域网接入点AP等)同时提供数据的传输和直流电源的供给,能在确保现有结构化布线安全的同时保证现有网络的正...以太网供电PoE(Power Over Ethernet)是一种局域网技术,通过现有的Cat5/Cat5e/Cat6以太网电缆给IP终端设备(如IP电话机、无线局域网接入点AP等)同时提供数据的传输和直流电源的供给,能在确保现有结构化布线安全的同时保证现有网络的正常运作,最大限度地降低成本。当前PoE技术已在企业与工业中得到广泛的应用,文中提出几种PoE设计方案,希望对PoE产品的开发有所帮助。展开更多
提出一种蓄电池充电控制芯片的设计,具有恒流、恒压、过压、浮充等多种不同充电模式,可以在外部微处理器的支持下针对不同种类电池和应用场合的需要实现电池的高效优化充电。讨论并给出了芯片的系统组成及主要电路的设计,在1.5μm 50 V ...提出一种蓄电池充电控制芯片的设计,具有恒流、恒压、过压、浮充等多种不同充电模式,可以在外部微处理器的支持下针对不同种类电池和应用场合的需要实现电池的高效优化充电。讨论并给出了芯片的系统组成及主要电路的设计,在1.5μm 50 V BCD(Bipolar-CMOS-DMOS)工艺下予以实现。测试结果表明芯片工作正常,电路功能及芯片预期的主要功能已成功实现。展开更多
This paper proposes a high-performance pulse-width modulation（PWM） AC/DC controller, which can drive a high-voltage（HV） 650-V power metal-oxide-semiconductor field-effect Transistor（MOSFET） in typical applicatio...This paper proposes a high-performance pulse-width modulation（PWM） AC/DC controller, which can drive a high-voltage（HV） 650-V power metal-oxide-semiconductor field-effect Transistor（MOSFET） in typical applications of adapters in portable electronic devices. In order to reduce the standby power consumption and improve the response speed in the start-up state, an improved under voltage lockout（UVLO） circuit without a voltage reference source or comparator is adopted. The AC/DC controller is fabricated using a 40-V 0.8-μm onepoly two-metal（1P2M） CMOS process, and it only occupies 1410 × 730 μm^2. A 12 V/2 A flyback topology for quick-charge application is illustrated as the test circuit, which is currently one of the most advanced power adapters in use. Test values show that the turn-on and the turn-off threshold voltages are 19.318 and 8.01 V, respectively. A high hysteresis voltage of 11.308 V causes the value of the power-charging capacitor to decrease to as low as 1 μF to reduce production cost. In addition, the start-up current of 2.3 μA is extremely small, and is attributed to a reduction in the system＇s standby power consumption. The final test results of the overall system are proven to meet the Energy Star Ⅵ standard. The controller has already been mass produced for industrial applications.展开更多
Highly reliable bandgap-based under-voltage-lockout （UVLO） methods are presented in this paper. The proposed under-voltage state to signal conversion methods take full advantages of the high temperature stability ch...Highly reliable bandgap-based under-voltage-lockout （UVLO） methods are presented in this paper. The proposed under-voltage state to signal conversion methods take full advantages of the high temperature stability characteristics and the enhancement low-voltage protection methods which protect the core circuit from error operation; moreover, a common-source stage amplifier method is introduced to expand the output voltage range. All of these methods are verified in a UVLO circuit fabricated with a 0.5 μm standard BCD process technology. The experimental result shows that the proposed bandgap method exhibits a good temperature coefficient of 20 ppm/℃, which ensures that the UVLO keeps a stable output until the under-voltage state changes. Moreover, at room temperature, the high threshold voltage VTH＋ generated by the UVLO is 12.3 V with maximum drift voltage of ±80 mV, and the low threshold voltage VTH- is 9.5 V with maximum drift voltage of±70 mV. Also, the low voltage protection method used in the circuit brings a high reliability when the supply voltage is very low.展开更多
基金Project supported by the National Natural Science Foundation of China(No.41274047)the Natural Science Foundation of Jiangsu Province(No.BK2012639)the Changzhou Science and Technology Support(Industrial)Project(No.CE20120074)
文摘A fully integrated LED driver based on a current mode PWM boost DC-DC converter with constant output current is proposed. In order to suppress the inrush of current and the overshoot voltage at the start up state, a soft-start circuit is adopted. Additionally, to adjust the LED brightness without color variation over the full dimming range and achieve high efficiency, a PWM dimming circuit is presented. Furthermore, to keep the loop stability of the LED driver, an internal slope compensation network is designed to avoid the sub-harmonic oscillation when the duty cycle exceeds 50%. Finally, a UVLO circuit is adopted to improve the reliability of the LED driver against the input voltage changing. The LED driver has been fabricated with a standard 0.5/xm CMOS process, and only occupies 1.21 × 0.76 mm^2. Experimental results show that the brightness of the LED can be adjusted by an off- chip PWM signal with a wide adjusting range. The inductor current and output current increase smoothly over the whole load range. The chip is in the UVLO condition when the input voltage is below 2.18 V and has achieved about 137 μs typical start-up time.
文摘We demonstrate the key module of comparators in GaN ICs,based on resistor-transistor logic(RTL)on E-mode wafers in this work.The fundamental inverters in the comparator consist of a p-GaN gate HEMT and a 2DEG resistor as the load.The function of the RTL comparators is finally verified by a undervoltage lockout(UVLO)circuit.The compatibility of this circuit with the current p-GaN technology paves the way for integrating logic ICs together with the power devices.
文摘以太网供电PoE(Power Over Ethernet)是一种局域网技术,通过现有的Cat5/Cat5e/Cat6以太网电缆给IP终端设备(如IP电话机、无线局域网接入点AP等)同时提供数据的传输和直流电源的供给,能在确保现有结构化布线安全的同时保证现有网络的正常运作,最大限度地降低成本。当前PoE技术已在企业与工业中得到广泛的应用,文中提出几种PoE设计方案,希望对PoE产品的开发有所帮助。
文摘提出一种蓄电池充电控制芯片的设计,具有恒流、恒压、过压、浮充等多种不同充电模式,可以在外部微处理器的支持下针对不同种类电池和应用场合的需要实现电池的高效优化充电。讨论并给出了芯片的系统组成及主要电路的设计,在1.5μm 50 V BCD(Bipolar-CMOS-DMOS)工艺下予以实现。测试结果表明芯片工作正常,电路功能及芯片预期的主要功能已成功实现。
文摘提出了一种基于标准CMOS工艺的电压检测VD(Voltage Detector)电路,具有高集成度、低功耗、检测点多档位可调节的特点。开关电容SC(Switched Capacitor)电路仅需一个低频时钟即可提供准确的电源分压,在低功耗应用中可以有效替代传统电阻分压。在3.3 V电源电压的MCU应用中,电压检测电路仅消耗几百n A的电流,对时钟变化不敏感(低频时钟频率变化范围4 k Hz^40 k Hz),并且响应时间在一个时钟周期内。
文摘This paper proposes a high-performance pulse-width modulation（PWM） AC/DC controller, which can drive a high-voltage（HV） 650-V power metal-oxide-semiconductor field-effect Transistor（MOSFET） in typical applications of adapters in portable electronic devices. In order to reduce the standby power consumption and improve the response speed in the start-up state, an improved under voltage lockout（UVLO） circuit without a voltage reference source or comparator is adopted. The AC/DC controller is fabricated using a 40-V 0.8-μm onepoly two-metal（1P2M） CMOS process, and it only occupies 1410 × 730 μm^2. A 12 V/2 A flyback topology for quick-charge application is illustrated as the test circuit, which is currently one of the most advanced power adapters in use. Test values show that the turn-on and the turn-off threshold voltages are 19.318 and 8.01 V, respectively. A high hysteresis voltage of 11.308 V causes the value of the power-charging capacitor to decrease to as low as 1 μF to reduce production cost. In addition, the start-up current of 2.3 μA is extremely small, and is attributed to a reduction in the system＇s standby power consumption. The final test results of the overall system are proven to meet the Energy Star Ⅵ standard. The controller has already been mass produced for industrial applications.
基金supported by the National Natural Science Foundation of China(No.61106026)
文摘Highly reliable bandgap-based under-voltage-lockout （UVLO） methods are presented in this paper. The proposed under-voltage state to signal conversion methods take full advantages of the high temperature stability characteristics and the enhancement low-voltage protection methods which protect the core circuit from error operation; moreover, a common-source stage amplifier method is introduced to expand the output voltage range. All of these methods are verified in a UVLO circuit fabricated with a 0.5 μm standard BCD process technology. The experimental result shows that the proposed bandgap method exhibits a good temperature coefficient of 20 ppm/℃, which ensures that the UVLO keeps a stable output until the under-voltage state changes. Moreover, at room temperature, the high threshold voltage VTH＋ generated by the UVLO is 12.3 V with maximum drift voltage of ±80 mV, and the low threshold voltage VTH- is 9.5 V with maximum drift voltage of±70 mV. Also, the low voltage protection method used in the circuit brings a high reliability when the supply voltage is very low.
