BQ77904, BQ77905
SLUSCM3K – JUNE 2016 – REVISED JULY 2020
BQ77904, BQ77905 3-Series to 20-Series Ultra Low-Power Voltage, Current, Temperature, and Open-Wire Stackable Lithium-Ion Battery Protector
1 Features
• NORMAL mode: 6 µA (BQ77904 and BQ77905) • Full suite of voltage, current, and temperature
protections • Scalable cell count from 3 series to 20 series or
more • Voltage protection (accuracy ±10 mV)
– Overvoltage: 3 V to 4. 575 V – Undervoltage: 1. 2 V to 3 V • Open cell and open-wire detection (OW) • Current Protection
– Overcurrent discharge 1: –10 mV to –85 mV – Overcurrent discharge 2: –20 mV to +170 mV – Short circuit discharge: –40 mV to +340 mV – Accuracy ±20% for ≤ 20 mV, ±30% for > 20 mV
across full temperature • Temperature protection
– Overtemperature charge: 45°C or 50°C – Overtemperature discharge: 65°C or 70°C – Undertemperature charge: –5°C or 0°C – Undertemperature discharge: –20°C or –10°C • Additional Features
– Independent charge (CHG) and discharge (DSG) FET drivers
– 36-V absolute maximum rating per cell input – Built-in-self-test functions for high reliability • SHUTDOWN mode: 0. 5-µA maximum • Functional Safety-Capable
– Documentation available to aid functional safety system design
2 Applications
• Power tools, garden tools • Start-stop battery packs • Lead-acid (PbA) replacement batteries • Light electric vehicles • Energy storage systems, uninterruptible power
supplies (UPS) • 10. 8-V to 72-V packs
3 Description
The BQ77904 and BQ77905 devices are low-power battery pack protectors that implement a suite of voltage, current, and temperature protections without microcontroller (MCU) control. The device's stackable interface provides simple scaling to support battery cell applications from 3 series to 20 series or more. Protection thresholds and delays are factory-programmed and available in a variety
of configurations. Separate overtemperature and undertemperature thresholds for discharge (OTD and UTD) and charge (OTC and UTC) are provide...