Texas Instruments BQ27545YZFR-G1

Overview

BQ27545YZFR-G1 from Texas Instruments is a single-cell Li-ion battery fuel gauge IC implementing Impedance Track™ technology for accurate state-of-charge (SOC), remaining capacity (mAh), time-to-empty (min), and temperature (°C) reporting. It integrates coulomb counting via 5–20 mΩ sense resistors, supports SHA-1/HMAC authentication, and resides inside battery packs or on mainboards with embedded non-removable batteries - used in smartphones, tablets, and handheld terminals.

For engineers reviewing the BQ27545YZFR-G1 datasheet, BQ27545YZFR-G1 pinout, BQ27545YZFR-G1 application, or BQ27545YZFR-G1 equivalent, key selection criteria include HDQ/I²C dual-interface support, ±1% SOC accuracy across lifetime, internal short/tab disconnection detection, low-power operating modes (down to 8 µA in HIBERNATE), and 15-ball DSBGA package compatibility with space-constrained portable designs.

Technical Context

The BQ27545YZFR-G1 employs a proprietary Impedance Track™ algorithm that models battery discharge curves using real-time voltage, current, and temperature measurements - dynamically adjusting for aging, self-discharge, and rate/temperature inefficiencies. Its integrating ADC provides 14–15-bit resolution for coulomb counting (SRP/SRN) and cell voltage/temperature sensing (BAT/TS), with <10 µV input offset on the sense path.

It features dual communication interfaces: HDQ (single-wire, open-drain) and I²C (400 kHz, open-drain SDA/SCL), both supporting host interrogation of Standard and Extended Commands. Power management includes four operational modes - NORMAL (118 µA), SLEEP (62 µA), FULLSLEEP (23 µA), and HIBERNATE (8 µA) - triggered automatically or via system control through CE and SE pins.

Key Specifications

Pinout & Package

Package: 15-ball Nano-Free™ DSBGA (YZF), 2.61 mm × 1.96 mm - ultra-compact footprint optimized for thin mobile devices.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ27545YZFR-G1, BQ27542-G1 omits authentication but retains identical gauging accuracy and interface compatibility, while BQ27530-G1 trades capacity headroom and security for smaller footprint - making each viable for distinct tiered design requirements.

Availability

BQ27545YZFR-G1 is available at Aetrix Electronics and suitable for smartphones, tablets, and handheld terminals requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing for production programs.

Supply support for BQ27545YZFR-G1 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 company specializing in analog, embedded processing, and power management technologies - serving automotive, industrial, and consumer markets with high-reliability silicon solutions.

The BQ27545YZFR-G1 belongs to TI's battery fuel gauge product line, engineered specifically for high-accuracy, maintenance-free Li-ion battery monitoring in space- and power-constrained portable electronics.

FAQ

What communication interfaces does the BQ27545YZFR-G1 support?

The BQ27545YZFR-G1 supports both HDQ (single-wire, open-drain) and I²C (400 kHz, open-drain SDA/SCL) interfaces. It ships preconfigured in I²C mode. HDQ provides simplified routing for space-limited layouts, while I²C enables faster command execution and broader MCU compatibility. Both interfaces access the same register map and data flash, allowing seamless firmware migration between modes.

How does the BQ27545YZFR-G1 achieve <1% state-of-charge accuracy?

The BQ27545YZFR-G1 achieves <1% SOC accuracy using Texas Instruments' patented Impedance Track™ algorithm, which continuously models battery impedance versus SOC, temperature, aging, and load history. It combines 14–15-bit coulomb counting (via SRP/SRN), precision BAT/TS ADC measurements, and on-device learning - eliminating reliance on fixed lookup tables or periodic full-charge recalibration required by simpler fuel gauges.

What is the purpose of the SE (Shutdown Enable) pin on the BQ27545YZFR-G1?

The SE pin on the BQ27545YZFR-G1 is a push-pull output that signals device status to the host system. It asserts active-low during internal fault conditions such as internal short detection ([ISD] flag) or tab disconnection ([TDD] flag). This enables system-level power management controllers to initiate safe shutdown sequences - a critical feature for protecting end-user devices and meeting UL/IEC safety compliance requirements.

Can the BQ27545YZFR-G1 operate with a 3.3-V host I²C bus?

Yes, the BQ27545YZFR-G1 supports I²C communication with a 3.3-V host bus. Its SDA and SCL pins are open-drain with VIH threshold of 1.2 V minimum and VOH of VCC–0.5 V, and it operates with VCC regulated at 2.5 V (from internal LDO). External 10-kΩ pullup resistors to VCC (not host VDD) ensure proper logic levels - avoiding level-shifter requirements in mixed-voltage systems.

Does the BQ27545YZFR-G1 require an external thermistor?

The BQ27545YZFR-G1 supports both external and internal temperature sensing. For highest accuracy, it is designed to interface with a 10 kΩ NTC thermistor (e.g., Semitec 103AT) on the TS pin. However, it also includes an internal temperature sensor usable when external sensing is impractical - though internal readings reflect die temperature rather than pack temperature, limiting their utility for precise thermal compensation in high-power applications.