BQ77915

• Ultra-low quiescent current: 8 µA typ. (NORMAL mode), 2 µA (HIBERNATE mode)
• Full suite of voltage, current, and temperature protections
• Smart passive cell balancing removes cell-to-cell imbalance
• Scalable cell count from 3 series to 20 series or more
• Voltage protection (accuracy ±10 mV for OV, ±18 mV for UV)
  • 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
• Temperature protection
  • Overtemperature charge: 45°C or 50°C
  • Overtemperature discharge: 65°C or 70°C
• Additional features:
  • Independent charge (CHG) and discharge (DSG) FET drivers
  • Smart cell balancing algorithm with integrated FETs (up to 50-mA balancing current), also supports external FETs for higher cell-balancing current
  • Ultra-low power HIBERNATE mode
  • High 36-V absolute maximum rating per cell input
  • Resistor programmable overcurrent (OCD1/2) delay
• SHUTDOWN mode: 0.5-µA maximum

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The BQ77915 device is a low-power battery pack protector that implements a suite of voltage, current, and temperature protections and a smart cell balancing algorithm 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 provided for added flexibility.

The device achieves pack protection via the integrated independent CHG and DSG low-side NMOS FET drivers, which may be disabled through two control pins. These control pins may also be used to achieve cell protection solutions for higher series (6 series and beyond) in a simple and economical manner. To do this, simply cascade a higher device CHG and DSG outputs to the immediate lower device control pins. For added flexibility, discharge overcurrent protection delays can be programmed using a resistor connected from the OCDP pin to VSS.

The BQ77915 protector achieves a smart passive cell-balancing algorithm via integrated FETs for cell balancing currents up to 50 mA. For higher cell-balancing current requirements, external FETs can be connected. A HIBERNATE mode intended for shipping and storage of the battery packs enables ultra-low power operation.

The BQ77915 protector is intended for battery packs where no host monitoring is required.