STMicroelectronics STC3115AIQT

Overview

STC3115AIQT from STMicroelectronics is a dedicated battery gas gauge IC for Li-ion/Li-polymer packs in handheld devices, integrating Coulomb counting, voltage-mode SOC estimation, and programmable low-battery alarm output. It delivers 0.25% battery voltage monitoring accuracy, 45 µA power-saving mode current, and supports dual-package options: 1.4 × 2.0 mm 10-bump CSP and 2.0 × 3.0 mm DFN10 - used in mobile phones and portable medical equipment.

For engineers reviewing the STC3115AIQT datasheet, STC3115AIQT pinout, STC3115AIQT application, or STC3115AIQT equivalent, key selection considerations include mixed-mode gas gauging architecture, I²C register-configurable alarm thresholds (SOC and voltage), internal 32.768 kHz timebase accuracy (±2.5%), and validated battery swap detection with BATD/CD pin functionality.

Technical Context

The STC3115AIQT implements a dual-algorithm gas gauge system: a 14-bit sigma-delta ADC performs current sensing (5.88 µV LSB, 500 ms conversion) and voltage measurement (2.20 mV LSB, ±0.5% accuracy), while an embedded OptimGauge™ algorithm fuses Coulomb count and OCV-based SOC estimation. Its internal temperature sensor (±3 °C accuracy, 1 °C resolution) enables real-time compensation without external components.

Operating modes are software-selectable via VMODE bit: mixed mode (Coulomb counter + voltage algorithm active, 100 µA avg.) for high-accuracy tracking during charge/discharge, and voltage-only mode (45 µA avg.) for standby. Alarm logic is fully configurable through REG_SOC_ALM (1% default) and REG_ALARM_VOLTAGE (3.00 V default), with open-drain ALM output requiring external pull-up.

Key Specifications

Pinout & Package

STC3115AIQT is available in two surface-mount packages: 1.4 × 2.0 mm 10-bump flip-chip CSP and 2.0 × 3.0 mm DFN10. Both packages share identical pin functions and I/O mapping per the official STMicroelectronics datasheet (DocID023755 Rev 9).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar battery fuel gauge applications.

Compared with BQ27426YZFT and MAX17048G+T, the STC3115AIQT uniquely integrates battery swap detection, dual-package flexibility, and a true open-drain alarm output - simplifying hardware design and reducing firmware overhead in cost-sensitive handheld platforms.

Availability

STC3115AIQT is available at Aetrix Electronics and suitable for mobile phones, portable medical equipment, and digital cameras requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for STC3115AIQT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in microcontrollers, analog ICs, and power management solutions for industrial, automotive, and consumer markets.

The STC3115 belongs to ST's battery management IC product line, designed specifically for high-accuracy, low-power fuel gauging in space-constrained portable electronics with Li-ion/Li-polymer batteries.

FAQ

What package variants does STC3115AIQT support?

STC3115AIQT is offered in two qualified packages: a 1.4 × 2.0 mm 10-bump flip-chip CSP and a 2.0 × 3.0 mm DFN10. Both share identical pinout, electrical characteristics, and thermal performance per STMicroelectronics DocID023755 Rev 9. The CSP variant targets ultra-compact designs, while the DFN10 eases assembly and improves thermal dissipation.

How does the STC3115AIQT handle battery replacement events?

The STC3115AIQT detects battery swaps using the BATD/CD pin in input mode, combined with internal logic that distinguishes between cold insertion and system reset. Upon valid battery insertion, it triggers robust OCV measurement and reinitializes SOC without relying on volatile memory - ensuring accurate state recovery even after full discharge.

Can the ALM pin signal both low-SOC and low-voltage conditions simultaneously?

Yes - the ALM pin is driven low if either the programmed SOC threshold (REG_SOC_ALM) or voltage threshold (REG_ALARM_VOLTAGE) is breached, provided ALM_ENA is set. The REG_CTRL register separately flags ALM_SOC and ALM_VOLT bits, allowing host firmware to determine which condition triggered the alarm and respond accordingly.

What is the role of the RSTIO pin beyond reset signaling?

RSTIO serves dual function: as an input, it senses external reset pulses to synchronize STC3115AIQT initialization; as an open-drain output, it asserts a reset signal to the host MCU upon internal fault detection or battery swap. Its hysteresis and timing alignment with internal state machine ensure glitch-free system-level reset coordination.