## Overview of the BQ27Z561-R2 The **BQ27Z561-R2** is a highly integrated, single-cell Impedance Track™ fuel gauge and protection solution. It is designed for lithium-ion (Li-Ion) and lithium-polymer (Li-Poly) battery packs, providing high-accuracy monitoring and advanced safety features. --- ### Key Electronic Functional Blocks | Component Block | Description | | :--- | :--- | | **Fuel Gauge Engine** | Utilizes the patented **Impedance Track™ algorithm** to provide real-time State-of-Charge (SoC) and State-of-Health (SoH) data. | | **ADC (Analog-to-Digital)** | High-resolution 16-bit Delta-Sigma ADC for precise voltage, current, and temperature measurement. | | **Integrated Protection** | Built-in high-side N-channel FET drivers to prevent overcharge, over-discharge, short-circuits, and extreme temperatures. | | **Authentication** | Includes SHA-1/HMAC authentication to ensure only authorized battery packs are used with the host device. | | **Communication Interface** | Primarily uses **I2C** for communicating with the host processor. | --- ### Technical Specifications | Parameter | Specification | | :--- | :--- | | **Supported Cell Chemistry** | Li-Ion, Li-Poly, LiFePO4 | | **Input Voltage Range** | 2.2 V to 5.5 V | | **Communication Protocol** | I2C (up to 400 kHz) | | **Current Sensing** | External sense resistor (typically 1 mΩ to 10 mΩ) | | **Package Type** | 12-ball DSBGA (1.6 mm x 2.0 mm) | --- ### Pin Configuration and Functionality The device uses a compact **12-ball grid array**. Below are the primary pins involved in the electronic operation: 1. **VC1/BAT:** Connects to the positive terminal of the single-cell battery for voltage sensing and power. 2. **SRP/SRN:** Differential input pins connected across the sense resistor to measure charging and discharging current. 3. **SCL/SDA:** Standard I2C clock and data lines for host communication. 4. **CHG/DSG:** High-side FET control pins that drive the protection MOSFETs to disconnect the battery during fault conditions. 5. **TS1:** Input for an external NTC thermistor to monitor cell temperature. --- ### Operating Modes The BQ27Z561-R2 manages power consumption through three distinct electronic states: * **NORMAL Mode:** The device performs continuous measurements and provides real-time updates. * **SLEEP Mode:** The device performs periodic measurements at a reduced rate to save power while maintaining SoC accuracy. * **SHUTDOWN Mode:** A ultra-low power state where the protection FETs are turned off to prevent battery drain during long-term storage.