Jiana Lou

A Multi-Mode Four-Switch Buck-Boost DC/DC Converter

Considering that the output voltage of battery will decline during its use, a four-switch buck-boost converter was proposed, which could provide stable output voltage over a wide voltage range of battery so as to extend the use time of battery and enhance its use efficiency. To improve the efficiency, the converter is designed to operate in multiple modes, which controlled by different strategies that depends upon the difference between output and input voltages as well as the different load conditions. As results, the proposed converter could provide a steady output voltage over the entire fluctuating range of battery voltage. The converter chip was designed in 1.5-mum BCD (Bipolar-CMOS-DMOS) technology and the expectations were well achieved.

A green-switch controller IC for cascade buck-boost converter with seamless transition over entire input and load range

To raise the utilization ratio of lithium-ion battery in portable devices, a novel green-switch controller IC is proposed to constitute a 4-switch cascade buck-boost prototype, which is capable of outputting non-inverting step down and step up voltages. According to the relations between the input and output voltages through duty ratio, a finite state machine automatically determines the work method of converter namely buck method, boost method or transition method by combining peak and valley current programmed mode so as to improve the line regulation over the entire input voltage range. A three-phase seamless transition method is introduced into the controller. Its additional advantage is to lower output ripples. Furthermore, a special burst mode is added to reduce the power consumption during light-load operation. An elaborately designed circuitry and rigorous stability analysis further improves the seamless performance. The controller IC is designed and fabricated in 1.5@mm BCD (Bipolar-CMOS-DMOS) technology with an area of 8.75mm^2 and applied to a 2.7V-4.2V/3.3V, maximum output power 1.65W buck-boost converter. It features over 90% conversion efficiency during normal application and still remains over 80% under standby mode. The experimental results show that all functional and performance targets are successfully achieved as expected.

Design of a Dual-mode Clock Generator based on a PLL Structure

A Dual-mode clock generator based on a PLL(phase locked Loop)was proposed. The circuit, which provides 400 KHz internal fixed frequency mode and external input mode with a phase-lockable frequency range from 400 KHz to 2 MHz, is applicable to SMPS (Switching Mode Power Supply) controller IC to optimize its performance. A novel oscillation generator for low frequency application is introduced. The circuit was designed under 1.5 um BCD (Bipolar-CMOS-DMOS) process technology. The simulation results show the circuit works well and achieves all expected functions.

Switch-mode multi-power-supply Li-ion battery charger with power-path management

A switch-mode Li-ion battery charger is proposed. It is suitable for input power supply of wall adaptor or USB port in modern portable apparatus. When it works under USB port supply, its input current is automatically limited at a presetting value. A power-path management is introduced in to realize charging and power supply simultaneously based on load priority. It also realizes smooth transition from constant current charging to constant voltage charging in switch mode controller. The proposed charger is designed and simulated in TSMC 0.35µm CMOS process and all the simulation results are consistent with expectations well.

Cell balancing management for battery pack

This paper presents a cell balancing management for battery pack. It is used for each cell in battery pack to protect pack from damages such as overheating and overvoltage taken by the different performances between different cells, it manages individual cell with CC-CV charging strategy, shunts charge current smoothly to protect every cell preferably; in order to be suitable for different charge conditions, the smooth shunting voltage reference is set by actual battery pack charge current. The design chooses Li-ion battery whose full voltage is 4.2v as the example. And the design is accomplished under the TSMC 0.35um technology.

High-conversion-ratio buck regulator for SoC in 0.13µm digital CMOS process

Aiming to SoC (System-on-Chip) power supply in portable devices, a high-conversion-ratio buck regulator is proposed. The operation duty cycle is expanded to 100% due to the emulated current mode. The 2.5V to 4.5V input voltage range makes it ideally suited for single cell Li-Ion battery supplied devices. The range of output voltage is from 1.2V to input voltage accord to different kinds of SoC IP cores. At the same time, a high efficiency light load operation is introduced in to prolong battery lifetime. To obtain good compatibility with digital systems, the proposed buck regulator is designed in SMIC 0.13µm standard digital CMOS process (the I/O can withstand an input voltage up to 4.6V). The simulation results are consistent with expectations well.

A nanopower single-trim voltage reference in a 0.13/im digital CMOS process

A nanopower single-trim CMOS voltage reference in SMIC 0.13/xm digital process is proposed. It utilizes a subthresh-old nMOSFET biased by a proportional to absolute temperature (PTAT) current to generate a negative temperature coefficient (TC) voltage, which is used to obtain a mutual compensating reference voltage together with a PTAT voltage. Simulated results indicate the proposed reference has a temperature coefficient of 4.82ppm/°C over the operating range from −20 to 80°C and a line regulation of 3.4mV/V over the supply range from 1.2 to 3V. The simulated power consumption is 648nW.

Power Supply Module for System on Chip with Wide Input Range

This paper presents a power supply module (PSM) for SoCs (system on chip). This module, which is based on an improved LDO, has a wide input range and switchable power path. The proposed PSM can output a steady voltage of 6v as input voltage varies between 5.7 V-30 V, with a max error of 4.3%. It also provides a flexible power path. The SoCs will be supplied by either internal LDO or external power supply directly in corresponding applications. Further more, because of fast step of load condition in SoCs, a speedup loop was introduced to increase the stabilizing speed of output voltage, and up to 26.9% boost can be achieved according to simulation. The design accomplished under the 1.5 um BCD (Bipolar-CMOS-DMOS) technology.