Texas Instruments BQ27742YZFR-G1

Overview

BQ27742YZFR-G1 from Texas Instruments is a single-cell Li-ion battery fuel gauge IC with integrated hardware protection, featuring Impedance Track™ technology for ±1% state-of-charge accuracy, 16-bit high-side coulomb counting (5–20 mΩ sense resistor), and programmable overvoltage (4.45 V), undervoltage (2.438 V), overcurrent (OCD: 14 mV, OCC: 6 mV), and short-circuit (SCD: 73 mV) protection - deployed in smartphones and tablets for runtime prediction and pack-level safety.

For engineers reviewing the BQ27742YZFR-G1 datasheet, BQ27742YZFR-G1 pinout, BQ27742YZFR-G1 application, or BQ27742YZFR-G1 equivalent, key selection criteria include I²C/HDQ dual-interface support, DSBGA-15 (2.78 mm × 1.96 mm) ultra-compact packaging, 40 µA FULLSLEEP current, and flash-based reprogrammability of protection thresholds without firmware changes.

Technical Context

The BQ27742YZFR-G1 integrates a precision 16-bit integrating ADC for coulomb counting and a separate 14–15-bit SAR ADC for cell voltage (VBAT), temperature (TS), and thermistor measurements. Its dual-oscillator architecture uses an 8.389 MHz high-frequency oscillator (±4.5% over –40°C to 85°C) and a 32.768 kHz low-frequency oscillator (±4.0%) to synchronize gauging and protection timing.

Hardware protection logic operates independently of the fuel gauge microcontroller core, with dedicated comparators and fixed-delay timers (tOVP = 1.00 s, tUVP = 31.25 ms, tOCD = 31.25 ms, tSCD = 312.5 µs). All protection thresholds are stored in 64-byte non-volatile data flash and configurable via host commands - enabling field updates to OVP/UVP/OCC/OCD/SCD trip points without hardware modification.

Key Specifications

Pinout & Package

Package: Ultra-compact 15-ball NanoFree™ DSBGA (YZF), body size 2.78 mm × 1.96 mm, 0.4 mm ball pitch, bottom-side thermal pad.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ27742YZFR-G1, the BQ27427YZFT-G1 trades compactness and dual-interface flexibility for easier soldering and thermal management, while the BQ27510-G3 offloads protection responsibility to the host system - making BQ27742YZFR-G1 optimal for space-constrained, self-contained battery packs requiring autonomous safety response.

Availability

BQ27742YZFR-G1 is available at Aetrix Electronics and suitable for smartphone, tablet, and handheld terminal designs requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing for automotive-qualified battery subsystems.

Supply support for BQ27742YZFR-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 leader specializing in analog, embedded processing, and power management technologies, with over 50 years of innovation in battery management systems.

The BQ27742YZFR-G1 belongs to TI's bq27xxx fuel gauge family, designed specifically for single-cell Li-ion battery packs in portable electronics - prioritizing accuracy, autonomy, and integration to eliminate external protection components.

FAQ

What protection functions does the BQ27742YZFR-G1 implement in hardware?

The BQ27742YZFR-G1 implements five hardware-based protections: overvoltage (OVP), undervoltage (UVP), overcurrent in charge (OCC), overcurrent in discharge (OCD), and short-circuit in discharge (SCD). Each uses dedicated analog comparators and fixed delay timers - for example, OCD triggers at 14 mV across SRP/SRN with 31.25 ms delay - and all thresholds are stored in non-volatile flash for field reconfiguration. The BQ27742YZFR-G1 executes these actions autonomously without host intervention.

How does Impedance Track™ technology improve fuel gauging accuracy in the BQ27742YZFR-G1?

Impedance Track™ models the battery's electrochemical impedance spectrum to predict voltage behavior under varying load, temperature, and aging conditions. Unlike voltage-based methods, it dynamically adjusts for capacity fade and rate-dependent voltage sag - delivering ±1% state-of-charge accuracy over the full life cycle. The BQ27742YZFR-G1 updates its model continuously using coulomb count and voltage/temperature measurements, eliminating manual calibration. This is validated across 500+ charge cycles in TI's characterization data.

Can the BQ27742YZFR-G1 operate without an external sense resistor?

No. The BQ27742YZFR-G1 requires an external high-side sense resistor (5–20 mΩ) connected between SRP and SRN to perform coulomb counting. Its integrating ADC measures the differential voltage across this resistor to compute charge flow. Removing the resistor disables current measurement, runtime estimation, and overcurrent protection functions. The BQ27742YZFR-G1 does not support zero-resistor or shuntless operation - all specified accuracy and protection features depend on this external component.

What are the voltage and timing requirements for the HDQ interface on the BQ27742YZFR-G1?

The HDQ interface on the BQ27742YZFR-G1 operates at VREG25 (2.5 V nominal) with open-drain signaling. Host-initiated '1' pulses must be 0.5–50 µs wide; '0' pulses 86–145 µs wide. Gauge responses use 32–50 µs for '1' and 80–145 µs for '0', with 190 µs minimum cycle time. HDQ reset requires a 1.8–2.2 s low pulse. Rise time to 1.2 V must be ≤950 ns. These values ensure reliable single-wire communication without clock skew or timing violations in noisy portable environments.

Does the BQ27742YZFR-G1 support SHA-1 authentication, and how is it implemented?

Yes, the BQ27742YZFR-G1 includes hardware-accelerated SHA-1 authentication using a 64-byte non-volatile scratch pad flash area. Keys and challenge-response data are stored in this protected memory region, and cryptographic operations execute internally without exposing secrets to the host. Authentication is triggered via specific extended data commands and used to verify genuine battery packs - preventing counterfeit substitution in branded devices. The BQ27742YZFR-G1 performs all hashing in dedicated logic, ensuring deterministic timing and side-channel resistance.