| Summary: | 碩士 === 中原大學 === 電子工程研究所 === 91 === Research on CMOS Micro Power Lithium-Ion Batteries Protection IC Design
Abstract
The aim of this research is to design a Lithium-ion batteries protection IC for portable device applications. The major concerns on design techniques for power and temperature independent circuits, micro power biasing skill and reliability enhancements for system performance have been implemented and investigated by using a double-poly double metal CMOS technology.
The protection system detects battery cell voltage and charge/discharge current. According to detected results, the state-machine has been initialized to drive the system to switch external MOSFET and charge/discharge current loop. The sample and latch concept has been used to implement voltage monitoring, and analog circuits based on weak inversion operation are also involved to realize micro power application. Main circuit blocks built in this research are wide-swing constant transconductance bias circuit, clock generator, divider, bandgap reference, switch capacitor voltage divider, hysteresis comparator, reverse bias protection circuit, and charge pump.
For the accuracy issue, the capacitor voltage divider is used to reduce the effects caused by temperature and process variation. The chopper-stabilized technique is adopted to eliminate the offset voltage of OP amplifier. For the reliability concern, all circuits are designed with the emphases of low operating voltage (1.5V) and high PSRR (>110dB) characteristics. Hysteresis circuits are used to avoid unexpected system shutdown, which might be caused by some parasitic effects. The reverse bias protection circuit is used to prevent unnecessary pn junction forward bias. A 3.6V micro power system with 6.57 uA operating current is built in this research。
Key word: Micro power, Lithium-Ion Batteries Protection, Weak Inversion.
|
|---|
