A 42 nJ/Conversion On-Demand State-of-Charge Indicator for Miniature IoT Li-Ion Batteries

Junwon Jeong, Seokhyeon Jeong, Dennis Sylvester, David Blaauw, Chulwoo Kim

Research output: Contribution to journalArticle

1 Citation (Scopus)


An energy-efficient state-of-charge (SOC) indication algorithm and integrated system for low-power wireless sensor nodes with the miniature Internet of Things (IoT) batteries are introduced in this paper. Based on the key findings that the miniature Li-ion batteries exhibit a fast response to the battery current transient, we propose an instantaneous linear extrapolation (ILE) algorithm and circuit system based on the ILE algorithm allowing accurate on-demand estimation of SOC. Due to the on-demand operation, an always-on current integration is avoided, reducing power and energy consumption by several orders of magnitude. Furthermore, the proposed SOC indicator does not require a battery disconnection from the load, ensuring continuous operation of the applications. The system is implemented in a 180-nm CMOS technology. The power consumption is 42 nW, and maximum SOC indication error is 1.7%. The minimum applicable battery capacity is as low as 2 μAh.

Original languageEnglish
JournalIEEE Journal of Solid-State Circuits
Publication statusAccepted/In press - 2018 Jan 1


  • Batteries
  • Battery
  • Battery charge measurement
  • fuel gauge
  • Internet of Things (IoT)
  • Li-ion battery
  • low power
  • Modulation
  • SOC indicator
  • State of charge
  • state of charge (SOC)
  • Temperature measurement
  • Wireless communication
  • Wireless sensor networks
  • wireless sensor node.

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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