Texas Instruments BQ2028YZGR

Overview

BQ2028YZGR from Texas Instruments is a 4-Kb serial EEPROM with integrated 2.5-V LDO regulator, single-wire HDQ interface, and die-temperature sensor-designed for battery pack-side nonvolatile storage and thermal monitoring in single-cell fuel gauge systems such as the bq27505-E1. It delivers 512 × 8-bit EEPROM, ±5°C temperature sensing range (–40°C to 85°C), and ultra-low 1-µA shutdown current.

For engineers reviewing the BQ2028YZGR datasheet, BQ2028YZGR pinout, BQ2028YZGR application, or BQ2028YZGR equivalent, this page provides verified functional context, validated pin roles, confirmed power-mode behavior, real-world integration constraints (e.g., HDQ pull-up, REGIN/VDD decoupling), and direct alternative part comparisons for battery management subsystem design.

Technical Context

The BQ2028YZGR implements a dual-oscillator architecture (32.768-kHz LFO and 8.389-MHz HFO) enabling dynamic power-mode selection-SHUTDOWN (LDO off), SLEEP (HFO off), IDLE, and active READ/WRITE-with automatic wake-up via HDQ break pulse. Its HDQ interface uses asynchronous return-to-one timing with CRC-8 data integrity verification over a single open-drain line.

EEPROM access follows a paged memory map (8 pages × 16 rows × 4 bytes), accessed through a 32-bit volatile buffer and controlled via HDQ command byte decoding (M-bit = 1 for mapped EEPROM, M-bit = 0 for registers). Temperature measurement uses a 10-bit ADC with programmable conversion speed (7.8–125 ms) and internal VDD or VREF selection.

Key Specifications

Pinout & Package

Package: 12-pin WCSP (YZG), 1490 × 2350 µm, 0.5-mm pitch, 0.625-mm max thickness.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar battery-pack NVM and temperature monitoring applications.

Compared with bq2027YZGT, BQ2028YZGR offers production-ready 3000-unit reel packaging and identical functionality; versus MAX17201, it preserves modular architecture with dedicated HDQ-based NVM, enabling independent firmware updates and legacy gauge interoperability without sacrificing thermal monitoring capability.

Availability

BQ2028YZGR is available at Aetrix Electronics and suitable for smart battery packs, fuel gauge calibration storage, and portable medical devices requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for BQ2028YZGR 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 broad industrial and automotive qualification.

The BQ2028YZGR belongs to TI's battery management IC portfolio, engineered specifically for pack-side intelligence-delivering secure, low-power, HDQ-compatible NVM and thermal sensing to complement system-side fuel gauges in space-constrained battery applications.

FAQ

What is the minimum external pull-up resistor value required for reliable HDQ communication with the BQ2028YZGR?

The BQ2028YZGR datasheet specifies a recommended HDQ external pull-up resistor range of 10 kΩ to 22 kΩ. A 10-kΩ, 5% resistor pulled to VDD is optimal for robust noise immunity and timing compliance across temperature and voltage extremes. Using values outside this range may cause tHW0/tHW1 timing violations or increased susceptibility to bus noise, especially in high-capacitance layouts exceeding 250 pF total HDQ loading.

How does the BQ2028YZGR handle EEPROM write integrity during power loss?

The BQ2028YZGR ensures EEPROM write integrity via a two-stage CRC-8 validation: first, the host writes target CRC to CRCT register; second, the device computes actual BUFFER CRC and compares it before initiating write. Only upon match does the device commit data to EEPROM and perform read-back verification. This prevents partial writes or corruption during VDD droop or HDQ interruption-critical for preserving calibration data in the BQ2028YZGR.

Can the BQ2028YZGR operate without an external crystal or oscillator?

Yes-the BQ2028YZGR contains fully integrated oscillators: a 32.768-kHz low-frequency oscillator (LFO) and an 8.389-MHz high-frequency oscillator (HFO), both with ±8% tolerance over –40°C to 85°C. No external timing components are needed for HDQ communication, temperature conversion, or EEPROM access. The BQ2028YZGR relies entirely on these on-die clocks, simplifying bill-of-materials and PCB layout.

What is the function of the TEST pins (TEST0–TEST3) on the BQ2028YZGR, and how should they be connected?

The TEST0–TEST3 pins on the BQ2028YZGR are reserved exclusively for factory test and are not functional in end-user applications. Per the datasheet, all four pins must be connected to VSS (ground) in the application circuit. Leaving them floating or connecting to other signals may cause undefined behavior, latch-up risk, or failure to enter proper power modes. Their presence reflects wafer-level testability-not user-accessible features-of the BQ2028YZGR.

Does the BQ2028YZGR support temperature measurement in shutdown mode?

No-the BQ2028YZGR disables the ADC, LFO, and HFO in SHUTDOWN mode to achieve 1-µA typical quiescent current. Temperature measurement requires active ADC operation, which only occurs in IDLE, READ, or WRITE modes. To obtain die temperature, the host must first wake the BQ2028YZGR from SHUTDOWN using an HDQ break pulse, then issue a CONV command via the Control register (0x05), wait for ADC_DRDY assertion, and read ADHI/ADLOW registers.