A PSR single-stage flyback LED driver with simple line regulation and quasi-resonant operation

A single-stage flyback driving integrated circuit （IC） for light-emitting diodes （LEDs） is proposed. With an average primary-side current estimation and negative feedback networks, the driver operates in the boundary conduction mode （BCM）, while the output current can be derived and regulated precisely. By means of a simple external resistor divider, a compensation voltage is produced on the ISEN pin during the turn-on period of the primary MOSFET to improve the line regulation performance. On the other hand, since the delay time between the time that the secondary diode current reaches zero and the turn-on time of the MOSFET can be automatically adjusted, the MOSFET can always turn on at the valley voltage even if the inductance of the primary winding varies with the output power, resulting in quasi-resonant switching for different primary inductances. The driving IC is fabricated in a Dongbu HiTek＇s 0.35μm bipolar-CMOS-DMOS process. An 18 W LED driver is finally built and tested. Results show that the driver has an average efficiency larger than 86%, a power factor larger than 0.97, and works under the universal input voltage （85-265 V） with the LED current variation within ±0.5%.

Hierarchical Task Planning for Power Line Flow Regulation

The complexity and uncertainty in power systems cause great challenges to controlling power grids.As a popular data-driven technique,deep reinforcement learning(DRL)attracts attention in the control of power grids.However,DRL has some inherent drawbacks in terms of data efficiency and explainability.This paper presents a novel hierarchical task planning(HTP)approach,bridging planning and DRL,to the task of power line flow regulation.First,we introduce a threelevel task hierarchy to model the task and model the sequence of task units on each level as a task planning-Markov decision processes(TP-MDPs).Second,we model the task as a sequential decision-making problem and introduce a higher planner and a lower planner in HTP to handle different levels of task units.In addition,we introduce a two-layer knowledge graph that can update dynamically during the planning procedure to assist HTP.Experimental results conducted on the IEEE 118-bus and IEEE 300-bus systems demonstrate our HTP approach outperforms proximal policy optimization,a state-of-the-art deep reinforcement learning(DRL)approach,improving efficiency by 26.16%and 6.86%on both systems.

Inducing fertility restoration in the genic male sterile line of rice with chemical regulators

For the first time, the fertility of rice genic male sterile line was partially restored with the application of chemical regulators at Hainan Rice Breeding Nursery on Mar 1993. A single panicle of the rice plant could bear as many as 27 grains. The chemical agent that could modulate the growth of the rice plants of genic male sterile line was developed by Prof ZHOU Guangqia and his colleagues at the Biology Institute, Hunan Teachers University, China.

Improvements in performance and reliability for segmented linear LED drivers

Several improvements have been made to the conventional segmented linear light-emitting diode （LED） driver topology to enhance the performance and reliability of the system. A compensation technology is proposed to adaptively adjust the impedance of the sensing circuit to keep the output luminance constant in case of line volt- age variations. Based on the proposed technology, an active over temperature protection technique is presented to constrain the averaged LED current according to the junction temperature to prevent the driving IC from overheating. Otherwise, a pulse width modulation dimming circuitry which is compatible with input logic level ranging from 1.8 to 20 V is proposed. The proposed technologies are implemented in a 1.0μm 5/20/500 V BCD technol- ogy with three high voltage MOSFETs integrated on chip. The experimental results show that within 220± 15% V, 50 Hz AC line-voltage variation, the output luminance is restrained to 4% in total. The output luminance can also be effectively controlled by the PWM dimming circuitry, and a dimming range of 95% is achieved with good linearity.

A multiple transistor combination low-voltage curvature-corrected bandgap reference

A new bandgap reference（BGR） curvature compensation technology is proposed,which is a kind of multiple transistor combination.On the basis of the existing first-order bandgap reference technology,a compensation current circuit consisting of a sink current branch and a source current branch is added.The BGR was designed and simulated by using Semiconductor Manufacturing International Corporation（SMIC） 0.18μm CMOS process.The simulation results showed that when the power supply voltage was 1 V,the temperature coefficient of the BGR was 2.08 ppm/℃with the temperature range from—40 to 125℃,the power supply rejection ratio （PSRR） was—64.77 dB and the linear regulation was 0.44 mV/V with the supply power changing from 0.85 to 1.8 V.

Negative voltage bandgap reference with multilevel curvature compensation technique

A novel high-order curvature compensation negative voltage bandgap reference （NBGR） based on a novel multilevel compensation technique is introduced. Employing an exponential curvature compensation （ECC） term with many high order terms in itself, in a lower temperature range （TR） and a multilevel curvature compen- sation （MLCC） term in a higher TR, a flattened and better effect of curvature compensation over the TR of 165℃ （--40 to 125 ℃） is realised. The MLCC circuit adds two convex curves by using two sub-threshold operated NMOS. The proposed NBGR implemented in the Central Semiconductor Manufacturing Corporation （CSMC） 0.5 #m BCD technology demonstrates an accurate voltage of-1.183 V with a temperature coefficient （TC） as low as 2.45 ppm/℃over the TR of 165℃ at a -5.0 V power supply; the line regulation is 3 mV/V from a -5 to -2 V supply voltage. The active area of the presented NBGR is 370×180 μm2.