Texas Instruments BQ26500PWR

Overview

BQ26500PWR from Texas Instruments is a standalone single-cell Li-Ion/Li-Pol battery gas gauge IC that reports accurate state-of-charge (SoC), cell voltage (±20 mV), temperature (±3 K), and time-to-empty without host processor calculations. It integrates coulometric current sensing via differential SRP/SRN inputs, features internal oscillator-based timing, and operates in four low-power modes - including Hibernate (<1.5 µA) - for portable power management in space-constrained battery packs.

For engineers reviewing the BQ26500PWR datasheet, BQ26500PWR pinout, BQ26500PWR application, or BQ26500PWR equivalent, key selection considerations include its HDQ one-wire interface (5 kbits/s), auto-calibrating voltage-to-frequency converter (VFC) with <15 µV offset, EEPROM-programmable digital magnitude filter, and support for battery pack-level capacity learning across −20°C to 70°C.

Technical Context

The BQ26500PWR implements a fully differential, dynamically balanced voltage-to-frequency converter (VFC) for continuous charge/discharge integration, eliminating waveform shape dependency and enabling accurate capacity tracking independent of load profile. Its autocalibrating architecture cancels internal VFC offset and applies real-time compensation for temperature, self-discharge, and discharge rate using stored EEPROM constants (TCOMP, DCOMP).

It communicates via a bi-directional HDQ serial interface (no external clock required), uses an integrated die temperature sensor (0.25 K resolution), and maintains RAM register integrity during brownout via RBI-supplied backup. The device supports programmable EDV1/EDVF thresholds, at-rate time-to-empty prediction, and flag-driven status reporting (e.g., CHGS, VDQ, CI) for system-level battery health monitoring.

Key Specifications

Pinout & Package

Package: 8-pin TSSOP (PW), tape-and-reel (R suffix), 3.0 mm × 4.4 mm body, 0.65 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ26500PWR, BQ27200YZFT trades EEPROM programmability and RBI backup for smaller size and lower quiescent current, while BQ27425YZFT replaces the VFC architecture with a model-based ADC approach - offering higher accuracy at the cost of increased host processing and calibration complexity.

Availability

BQ26500PWR is available at Aetrix Electronics and suitable for smartphone battery packs, digital camera power systems, PDA energy monitoring, MP3 player runtime estimation, and handheld medical device battery management requiring stable component supply and long-lifecycle support.

Supply support for BQ26500PWR 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, with leadership in battery management ICs since the early 2000s.

The BQ26500PWR belongs to TI's bqJUNIOR family - designed specifically for cost-sensitive, space-constrained portable applications requiring high-accuracy standalone fuel gauging without host computational overhead.

FAQ

What is the primary function of the BQ26500PWR in a battery pack?

The BQ26500PWR serves as a standalone fuel gauge IC that measures and reports battery state-of-charge, voltage, temperature, and time-to-empty using an integrated voltage-to-frequency converter and HDQ interface. It eliminates the need for host processor-based Coulomb counting by performing all compensation - including temperature, self-discharge, and discharge rate - internally. The BQ26500PWR achieves this with no external crystal, minimal external components, and ultra-low quiescent current in Hibernate mode.

How does the BQ26500PWR handle current sensing accuracy without factory calibration?

The BQ26500PWR uses an auto-compensating voltage-to-frequency converter (VFC) that cancels internal offset voltage across SRP and SRN pins during normal operation. This eliminates the need for factory offset calibration. The device also supports a programmable Digital Magnitude Filter (DMF) to ignore sub-threshold counts caused by residual PCB layout offset. The BQ26500PWR specifies <15 µV typical VFC offset and maintains ±20 mV voltage accuracy over temperature - all verified per SLUS567A test conditions.

Can the BQ26500PWR operate without an external microcontroller?

Yes - the BQ26500PWR is a fully autonomous gas gauge IC. It performs all capacity calculations, temperature/voltage compensation, and capacity learning internally. While it communicates via HDQ to a host for register read/write, no host intervention is required for basic SoC reporting. The BQ26500PWR outputs ready-to-use values like RSOC (%), ARTTE (minutes), and FLAGS (CHGS, VDQ, CI) directly through its HDQ interface, enabling simple polling without complex firmware.

What is the role of the RBI pin on the BQ26500PWR?

The RBI (Register Backup Input) pin on the BQ26500PWR provides backup voltage to retain RAM register contents - including NAC, LMD, and FLAGS - during VCC brownout or battery removal. When VCC drops below the POR threshold (2.05–2.55 V), the BQ26500PWR draws power from an external capacitor connected to RBI, allowing data retention down to 1.3 V. This ensures learned capacity and status flags persist across power cycles, which is essential for accurate long-term SoC tracking in removable battery packs.

Does the BQ26500PWR support EEPROM reprogramming in the field?

Yes - the BQ26500PWR supports in-system EEPROM programming via the GPIO pin, which accepts 20–22 V programming voltage (VPROG) with 3 mA current. This enables field updates to critical parameters such as EDV1/EDVF thresholds, taper current, digital magnitude filter, and temperature compensation constants. Programming is limited to 10 cycles with 10-year data retention at 85°C, and requires controlled timing (tPROG = 20–100 ms) as specified in SLUS567A Section 3.