A high performance adaptive on-time controlled valley-current-mode DC–DC buck converter

This paper presents an AOT-controlled(adaptive-on-time,AOT)valley-current-mode buck converter for portable application.The buck converter with synchronous rectifier not only uses valley-current-mode control but also possesses hybridmode control functions at the same time.Due to the presence of the zero-current detection circuit,the converter can switch freely between the two operating modes without the need for an external mode selection circuit,which further reduces the design difficulty and chip area.The converter for the application of high power efficiency and wide current range is used to generate the voltage of 0.6–3.0 V with a battery source of 3.3–5.0 V,while the load current range is 0.05–2 A.The circuit can work in continuous conduction mode with constant frequency in high load current range.In addition,a stable output voltage can be obtained with small voltage ripple.In pace with the load current decreases to a critical value,the converter transforms into the discontinuous conduction mode smoothly.As the switching period increases,the switching loss decreases,which can significantly improve the conversion efficiency.The proposed AOT controlled valley current mode buck converter is integrated with standard 0.18μm process and the simulation results show that the converter provides well-loaded regulations with power efficiency over 95%.When the circuit switches between the two conduction modes drastically,the response time can be controlled within 30μs.The undershoot voltage is controlled within 25 mV under a large current hopping range.

High-power microwaves response characteristics of silicon and GaAs solar cells

The high-power microwave(HPM)effect heats solar cells,which is an important component of a satellite.This creates a serious reliability problem and affects the normal operation of a satellite.In this paper,the different HPM response characteristics of two kinds of solar cells are comparatively researched by simulation.The results show that there are similarities and differences in hot spot distribution and damage mechanisms between both kinds of solar cell,which are related to the amplitude of HPM.In addition,the duty cycle of repetition frequency contributes more to the temperature accumulation of the solar cells than the carrier frequency.These results will help future research of damage assessment technology,reliability enhancement and the selection of materials for solar cells.

A high EMS daisy-chain SPI interface for battery monitor system

A high EMS current-mode SPI interface for battery monitor IC（BMIC） is presented to form a daisychain bus configuration for the cascaded BMICs and the communication between the MCU and master BMIC.Based on analog and digital mixed filtering technique,the proposed daisy-chain can avoid the isolated communication issue in electromagnetic interference environment,and reduce the extensively required I/O ports of MCU,at the same time reduce the system cost.The proposed daisy-chain interface was introduced in a 6-ch battery monitor IC which was fabricated with 0.35μ m 30 V BCD process.The measurement result shows that the presented daisy-chain SPI interface achieves better EMS performance with different EMI injection while just consuming a total operation current up to 1 m A.

The influence of pulsed parameters on the damage of a Darlington transistor

Theoretical research on the heat accumulation effect of a Darlington transistor induced by high power microwave is conducted,and temperature variation as functions of pulse repetitive frequency（PRF）and duty cycle（DC）are studied.According to the distribution of the electronic field and the current density in the Darlington transistor,the research of the damage mechanism is carried out.The results show that for repetitive pulses with the same pulse widths and different PRFs,the value of temperature variation increases with PRF increases,and the peak temperature has almost no change when PRF is lower than 200 k Hz;while for the repetitive pulses with the same PRF and different pulse widths,the larger the pulse width is,the greater temperature variation varies.The response of the peak temperature caused by a single pulse demonstrates that there is no temperature variation when the rising time is much shorter than the falling time.In addition,the relationship between the temperature variation and the time during the rising edge time as well as that between the temperature variation and the time during the falling edge time are obtained utilizing the curve fitting method.Finally,for a certain average power,with DC increases the value of temperature variation decreases.

60 V tolerance full symmetrical switch for battery monitor IC

For stacked battery monitoring IC high speed and high precision voltage acquisition requirements,this paper introduces a kind of symmetrical type high voltage switch circuit.This kind of switch circuit uses the voltage following structure,which eliminates the leakage path of input signals.At the same time,this circuit adopts a high speed charge pump structure,in any case the input signal voltage is higher than the supply voltage,it can fast and accurately turn on high voltage MOS devices,and convert the battery voltage to an analog to digital converter.The proposed high voltage full symmetry switch has been implemented in a 0.18 μm BCD process;simulated and measured results show that the proposed switch can always work properly regardless of the polarity of the voltage difference between the input signal ports and an input signal higher than the power supply.