STMicroelectronics STC3100IST

Overview

STC3100IST from STMicroelectronics is a single-cell Li-ion battery monitor IC with integrated Coulomb counter and gas gauge functionality. It performs simultaneous voltage (0–5 V range, ±0.5% accuracy), temperature (±3°C), and current sensing (±80 mV input, 12–14-bit ADC) using an external 10–50 mΩ sense resistor, enabling up to ±7000 mAh capacity tracking at 0.2 mAh resolution in portable electronics.

For engineers reviewing the STC3100IST datasheet, STC3100IST pinout, STC3100IST application, or STC3100IST equivalent, key selection considerations include I²C-based register access (70h default address), dual timebase support (internal 32.768 kHz oscillator or external clock), 32-byte RAM for battery aging data, and open-drain IO0 for host signaling in space-constrained battery packs.

Technical Context

The STC3100IST implements a dedicated 12–14-bit signed ADC for current integration (gas gauge), paired with a separate 11-bit unsigned ADC for concurrent battery voltage and temperature monitoring - both operating on shared 32.768 Hz timing but with independent conversion cycles (125–500 ms for current; 250 ms for voltage/temp). The 28-bit charge accumulator updates via two's complement arithmetic and is readable as upper 16 bits over I²C.

Its functional architecture separates sensing paths: CG pin accepts differential current-sense voltage, VIN monitors battery voltage directly, and internal temperature sensing shares the same ADC MUX. The device supports calibration via CG_CAL bit to nullify ADC offset (±2–3 LSB), and retains register state down to 2.0 V VCC for deep-discharge recovery integrity.

Key Specifications

Pinout & Package

STC3100IST is housed in MiniSO-8 (plastic micropackage), 3.0 mm × 4.9 mm body, 0.65 mm pitch, ECOPACK®-compliant. Pin 1 (IO0) is top-left in standard top-view orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ27426YZFT and MAX17048G+T, the STC3100IST uniquely combines external clock synchronization, on-the-fly ADC offset calibration, and sub-2.0 V RAM retention - making it optimal for serviceable, field-upgradable battery packs requiring long-term accuracy stability.

Availability

STC3100IST is available at Aetrix Electronics and suitable for smartphone battery management, Bluetooth headset power monitoring, digital camera battery packs, and USB-C portable power banks requiring stable component supply and long-lifecycle support.

Supply support for STC3100IST 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The STC3100 belongs to ST's battery management IC product line, engineered specifically for high-accuracy, low-power single-cell Li-ion gas gauging in portable electronics where board space, thermal constraints, and firmware flexibility are critical.

FAQ

What is the function of the ROSC pin on the STC3100IST?

The ROSC pin serves a dual role: it either connects a 200 kΩ precision resistor to bias the internal 32.768 kHz oscillator, or accepts an external 30–70 kHz clock signal for improved gas gauge timing accuracy. When configured for external clock, the internal oscillator is disabled, reducing jitter-induced charge integration error to ±1%.

How does the STC3100IST maintain accuracy during temperature variation?

The STC3100IST uses a dedicated internal temperature sensor (±3°C accuracy) and concurrent voltage/temperature ADC sampling to feed correction factors into the gas gauge algorithm. Its 12–14-bit current ADC includes programmable offset calibration (via CG_CAL bit) to nullify thermal drift in the front-end amplifier, ensuring consistent 0.2 mAh resolution across −40°C to +85°C.

Can the STC3100IST operate without an external sense resistor?

No - the STC3100IST requires an external 10–50 mΩ sense resistor between the battery terminal and load path to generate the ±80 mV differential voltage applied to the CG pin. Without this resistor, current measurement and Coulomb counting are impossible; the device will still monitor voltage and temperature but cannot report charge state.

What happens to register contents during brown-out conditions?

All 32 RAM registers and control registers retain their values down to 2.0 V VCC, preserving battery cycle count, aging data, and configuration settings during low-voltage events. Below 2.0 V, registers reset to power-on defaults - a deliberate design to indicate irreversible deep discharge that may damage the Li-ion cell.