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BQ77904

ACTIVE

3-4S Low-Power Protector

Product details

Function Protection Number of series cells (min) 3, 4 Number of series cells (max) 4 Features FET drive, Open wire (OW), Over-temperature (OT), Overcurrent during discharge (OCD), Overvoltage, Short-circuit Discharge (SCD), Stackable, Under-temperature (UT), Undervoltage Operating current (typ) (µA) 6 Rating Catalog Vin (max) (V) 25 TI functional safety category Functional Safety-Capable Overvoltage protection 4.225 Operating temperature range (°C) -40 to 85 Battery overvoltage protection (min) (V) 3 Battery overvoltage protection (max) (V) 4.575
Function Protection Number of series cells (min) 3, 4 Number of series cells (max) 4 Features FET drive, Open wire (OW), Over-temperature (OT), Overcurrent during discharge (OCD), Overvoltage, Short-circuit Discharge (SCD), Stackable, Under-temperature (UT), Undervoltage Operating current (typ) (µA) 6 Rating Catalog Vin (max) (V) 25 TI functional safety category Functional Safety-Capable Overvoltage protection 4.225 Operating temperature range (°C) -40 to 85 Battery overvoltage protection (min) (V) 3 Battery overvoltage protection (max) (V) 4.575
TSSOP (PW) 20 41.6 mm² 6.5 x 6.4
  • 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
  • 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

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 provided for added flexibility.

The device achieves pack protection through 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 a reduced component count, all protection faults use internal delay timers.

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 provided for added flexibility.

The device achieves pack protection through 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 a reduced component count, all protection faults use internal delay timers.

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Technical documentation

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Type Title Date
* Data sheet BQ77904, BQ77905 3-Series to 20-Series Ultra Low-Power Voltage, Current, Temperature, and Open-Wire Stackable Lithium-Ion Battery Protector datasheet (Rev. K) PDF | HTML 31 Jul 2020
Functional safety information BQ77905 Function Safety Capable 13 Jul 2020
Application note bq77905 Pin Equivalent Diagrams 28 Nov 2017
Application note bq77905 Shutdown for Current Reduction 21 Jul 2017

Design & development

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Evaluation board

BQ77905EVM-707 — bq77905 3- to 5-Series Advanced Stackable Low-Power Battery Protector Evaluation Module

The bq77905EVM-707 is an evaluation board for the bq77905, low power battery protector IC.  The bq77905 IC supports 3-5S battery cell configurations and can be stacked to support comfortably a full stack of 20 series cells. In addition, the bq77905 implements a suite of voltage, current and (...)

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TSSOP (PW) 20 View options

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