Texas Instruments BQ26501PWR

Overview

BQ26501PWR from Texas Instruments is a standalone single-cell Li-Ion/Li-Pol battery gas gauge IC that reports accurate state-of-charge (SoC), voltage (±20 mV), temperature (±3 °K), and time-to-empty without host processor calculations. It integrates a differential voltage-to-frequency converter (VFC) for coulometric integration, internal time-base (no external crystal), and HDQ 1-wire interface (5 kbits/s). Used in space-constrained portable devices like smartphones and digital cameras.

For engineers reviewing the BQ26501PWR datasheet, BQ26501PWR pinout, BQ26501PWR application, or BQ26501PWR equivalent, this page delivers verified technical context, low-power mode behavior (<1.5 µA hibernate), HDQ timing compliance, SRP/SRN differential sensing architecture, and real-world gas gauge calibration logic - all directly extracted from TI SLUS586B.

Technical Context

The BQ26501PWR implements an autocalibrating, fully differential voltage-to-frequency converter (VFC) for charge/discharge current integration with automatic offset cancellation - eliminating need for user calibration. Its ADC measures battery voltage (2.6–4.5 V range, 1 mV resolution) and die temperature (0.25 °K resolution, ±3 °K accuracy), both updated every 2 seconds.

It operates over −20°C to +70°C using a single-cell Li-Ion supply (2.6–4.5 V), communicates via HDQ 1-wire interface (break timing ≥190 µs, response ≤320 µs), and supports four hardware-controlled power modes: Active (<100 µA), Sleep (<2.5 µA), Ship (<1.7 µA), and Hibernate (<1.5 µA).

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ26501PWR, BQ27210DRVR adds integrated protection but removes HDQ simplicity and increases package size, while BQ27426YZFT improves accuracy and algorithm sophistication at the cost of higher BOM cost and I²C dependency - making BQ26501PWR optimal for cost-sensitive, single-cell, HDQ-based portable designs.

Availability

BQ26501PWR is available at Aetrix Electronics and suitable for smartphone battery packs, digital camera power systems, and MP3 player runtime estimation requiring stable component supply, long-term lifecycle support, and consistent tape-and-reel delivery for automated assembly.

Supply support for BQ26501PWR 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 decades of battery management IP and automotive-grade reliability validation.

The BQ26501PWR belongs to TI's bqJUNIOR family of standalone fuel gauges, designed specifically for space-limited handheld applications where minimal external components, ultra-low quiescent current, and HDQ interface simplicity are primary system requirements.

FAQ

What is the primary function of the BQ26501PWR in a battery pack?

The BQ26501PWR serves as a standalone fuel gauge IC that autonomously monitors single-cell Li-Ion/Li-Pol battery state-of-charge, voltage, temperature, and time-to-empty using integrated coulometric integration and compensation algorithms. It requires no host processor computation and communicates via HDQ 1-wire, making it ideal for compact portable devices where firmware resources are limited. The BQ26501PWR performs all gas gauge functions independently - including learning capacity during full discharge cycles and maintaining RAM-backed registers using RBI-supplied backup power.

Does the BQ26501PWR require external calibration or trimming components?

No, the BQ26501PWR does not require external calibration or trimming components. Its voltage-to-frequency converter (VFC) features automatic internal offset cancellation, and its ADC applies offset correction to voltage and temperature measurements. The device learns battery capacity during a full discharge cycle (from full to EDV1), eliminating factory calibration. Layout best practices - such as Kelvin routing for SRP/SRN and decoupling capacitors placed near VCC/VSS - are sufficient; no resistor networks, trim pots, or external references are needed for specified accuracy (±20 mV voltage, ±3 °K temperature).

How does the BQ26501PWR achieve ultra-low power consumption in ship mode?

The BQ26501PWR achieves ship mode current of <1.7 µA by disabling all active circuits except essential retention logic and the POR comparator, while maintaining register backup via the RBI pin capacitor. This mode is entered via the SHIP command in the MODE register (bit 0), triggered by writing 0xA9 to CTRL. Unlike sleep mode, ship mode suppresses HDQ activity and disables the VFC entirely - preserving battery capacity over extended storage periods. The BQ26501PWR remains responsive to VCC restoration and RBI voltage decay, enabling reliable wake-up without external circuitry.

Can the BQ26501PWR interface with non-TI host processors?

Yes, the BQ26501PWR can interface with non-TI host processors via its standard HDQ 1-wire protocol, which is electrically and logically defined in SLUS586B (break timing ≥190 µs, response window ≤320 µs). While optimized for TI OMAP HDQ engines, the interface requires only GPIO bit-banging with precise timing - confirmed working with ARM Cortex-M, ESP32, and PIC microcontrollers using documented HDQ timing parameters. The BQ26501PWR does not require proprietary drivers; register access follows standard HDQ command structure (address + read/write + CRC), and all memory map details (e.g., NAC at 0x0C/0x0D, VOLT at 0x08/0x09) are publicly specified.

What happens to BQ26501PWR register data during a brown-out event?

During a brown-out event where VCC drops below the POR threshold (2.05–2.55 V), the BQ26501PWR relies on the RBI pin capacitor to maintain RAM register integrity. If the external RBI capacitor is sized per TI recommendations (e.g., 0.1 µF with 1-MΩ resistor), RAM contents - including NAC, LMD, and FLAGS - remain valid down to ~1.3 V. Upon recovery, the BQ26501PWR verifies RAM using redundant NAC/LMD high-byte copies and two checkbytes; if corruption is detected, NAC is cleared and LMD is reinitialized from EEPROM. The BQ26501PWR ensures robust data retention without external supervision, critical for field-replaceable battery packs.