An ultra-compact and efficient Li-ion battery charger circuit for biomedical applications
Author(s)
Do Valle, Bruno Guimaraes; Wentz, Christian T.; Sarpeshkar, Rahul
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This paper describes an ultra-compact analog lithium-ion (Li-ion) battery charger for wirelessly powered implantable medical devices. The charger presented here takes advantage of the tanh output current profile of an operational transconductance amplifier (OTA) to smoothly transition between constant current (CC) and constant voltage (CV) charging regimes without the need for additional area- and power-consuming control circuitry. The proposed design eliminates the need for sense resistors in either the charging path or control loop by utilizing a current comparator to detect end-of-charge. The power management chip was fabricated in an AMI 0.5 μm CMOS process, consuming 0.15 mm[superscript 2] of area. This figure represents an order of magnitude reduction in area from previous designs. An initial proof-of-concept design achieved 75% power efficiency and charging voltage accuracy of 99.8% relative to the target 4.2 V.
Date issued
2010-08Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer ScienceJournal
Proceedings of 2010 IEEE International Symposium on Circuits and Systems (ISCAS)
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Citation
Valle, Bruno Do, Christian T. Wentz, and Rahul Sarpeshkar. “An Ultra-compact and Efficient Li-ion Battery Charger Circuit for Biomedical Applications.” Proceedings of 2010 IEEE International Symposium on Circuits and Systems (ISCAS). 1224–1227. © Copyright 2010 IEEE
Version: Final published version
ISBN
978-1-4244-5309-2
978-1-4244-5308-5