Texas Instruments BQ29312ARTHR

Overview

BQ29312ARTHR from Texas Instruments is a 2-, 3-, or 4-cell lithium-ion/polymer battery protection analog front-end (AFE) IC with integrated 3.3-V/25-mA LDO, I²C-compatible interface, and programmable overcurrent/short-circuit protection. It monitors individual cell voltages (VC1–VC5), supports cell balancing via internal FETs (R_DS(on) = 400 Ω typ), and delivers <1% error capacity prediction when paired with bq2084 gas gauge. Used in notebook PCs and portable medical instrumentation for pack-level safety control.

For engineers reviewing the BQ29312ARTHR datasheet, BQ29312ARTHR pinout, BQ29312ARTHR application, or BQ29312ARTHR equivalent, this page provides verified technical context, exact pin functions per QFN-24 (RTH) package, real-world power mode behavior (Normal/Sleep/Ship), confirmed cell voltage scaling (0.150 V/V ±0.002), and validated alternatives for multi-cell Li-ion protection AFE selection.

Technical Context

The BQ29312ARTHR implements dual-tier overcurrent protection: programmable overload detection (50–205 mV, 5-mV steps, 10-mV hysteresis) and direction-specific short-circuit detection (100–475 mV, 25-mV steps, 50-mV hysteresis), each with independent blanking delays (1–31 ms for OL; 0–915 µs for SC). Its 32-kHz WDI input serves both watchdog timing and fault delay generation.

Cell voltage monitoring uses an inverted translation amplifier (V_{CELL_OUT} = –K × V_{CELL_IN} + 0.975 V) with K = 0.150 ±0.002, enabling host MCU ADC measurement of 0–4.5 V scaled outputs. Cell balancing is controlled via I²C-accessible CELL_SEL register bits 4–7, driving internal bypass FETs with external current-limiting resistors.

Key Specifications

Pinout & Package

Package: QFN-24 (RTH), 4 mm × 4 mm, 0.5-mm pitch, exposed thermal pad. Pinout validated per TI SLUS629A Rev. August 2005, Figure 1 (RTH top view).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-cell Li-ion protection AFE applications.

Compared with BQ29312ARTHR, BQ29330RHLR adds 5-V LDO and thermal shutdown headroom but increases BOM cost, while MP26028DJ-LF-Z sacrifices configurability and balancing for footprint reduction - making BQ29312ARTHR optimal for balanced feature set and QFN-24 compatibility in 2–4S systems.

Availability

BQ29312ARTHR is available at Aetrix Electronics and suitable for notebook PC battery management, portable medical instrumentation, and industrial test equipment requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for BQ29312ARTHR 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

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in battery management ICs and power solutions.

The BQ29312ARTHR belongs to TI's battery protection AFE product line, designed specifically for high-accuracy, programmable safety monitoring in 2–4S lithium-ion and lithium-polymer battery packs used in portable computing and medical devices.

FAQ

What is the primary function of the BQ29312ARTHR in a battery pack?

The BQ29312ARTHR serves as a protection analog front-end IC that monitors individual cell voltages, detects overcurrent/short-circuit events, controls external FETs for charge/discharge path management, and provides a calibrated I²C interface to host controllers. It integrates a 3.3-V LDO, thermistor bias, and cell balancing drive - all essential for safe, reliable operation of 2–4S Li-ion packs. The BQ29312ARTHR does not perform fuel gauging but feeds precise voltage data to companion gas gauge ICs like the bq2084.

How does the BQ29312ARTHR support zero-volt charging?

The BQ29312ARTHR supports zero-volt charging via its dedicated ZVCHG pin and associated FET driver, which remains functional even when pack voltage drops to 0 V. When enabled, the ZVCHG FET allows a compatible charger to apply precharge current directly to the battery terminals before normal charging begins. This capability is critical for recovering deeply discharged Li-ion cells without risking damage. The BQ29312ARTHR itself does not regulate the precharge current - that function resides in the external charger, while the BQ29312ARTHR provides the necessary gate drive and safety interlock.

What are the key differences between Normal, Sleep, and Ship power modes in the BQ29312ARTHR?

In Normal mode, the BQ29312ARTHR fully operates all protection, monitoring, and communication functions with 60-µA typical supply current. Sleep mode disables FET outputs and fault detection (OL/SC/watchdog) while retaining I²C access and RAM configuration, drawing 20–40 µA. Ship mode shuts down REG, disables I²C, and invalidates memory, reducing current to 0.1–1.0 µA for long-term storage. Entry into each mode is controlled by SLEEP pin state and STATE CTL register bits - the BQ29312ARTHR exits Sleep mode automatically upon SLEEP pin transition, but Ship mode requires pack voltage restoration.

Can the BQ29312ARTHR be used with a 2-cell battery configuration?

Yes, the BQ29312ARTHR supports 2-cell configurations by connecting VC1 and VC2 to the same node (the most-positive cell terminal) and leaving VC3–VC5 unconnected or tied appropriately per TI application guidance. In this setup, the IC measures the single cell voltage twice (via VC1–VC2 and VC2–VC3) and uses internal logic to derive valid pack and cell data. All protection features - including overload, short-circuit, and cell balancing - remain fully functional. The BQ29312ARTHR datasheet explicitly lists "2-, 3-, or 4-Cell Series Protection Control" as a core capability, confirming native 2S support without firmware modification.

What is the role of the WDI pin on the BQ29312ARTHR?

The WDI (Watchdog Input) pin on the BQ29312ARTHR accepts a 32.768-kHz clock signal that serves two critical timing functions: it establishes the blanking delay for overload and short-circuit detection, and it acts as the system watchdog timer. During startup, absence of WDI clock for >700 ms forces CHG/DSG/ZVCHG FETs OFF. After startup, a missing clock for >100 µs triggers watchdog timeout and FET shutdown. This dual-use design ensures deterministic fault response timing while minimizing external components - the WDI signal must be provided by the host microcontroller or a dedicated oscillator, and its presence is mandatory for reliable BQ29312ARTHR operation.