3-4S Low Power Protector - BQ77904

BQ77904 (ACTIVE)

3-4S Low Power Protector

 

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 S to 20 S 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 S 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 reduced component count, all protection faults use internal delay timers.

Features

  • Normal Mode: 6 µA (bq77904/bq77905)
  • Full suite of voltage, current and temperature protections
  • Scalable cell count from 3 S to 20 S 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

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Parametrics Compare all products in Battery Monitor, Protection & Authentication Solutions

 
Function
# Series Cells (Min)
# Series Cells (Max)
Communication Interface
Protection Feature(s)
Special Features
Typical Operating Current (Typ) (uA)
Vin (Max) (V)
Rating
Pin/Package
BQ77904 BQ77905
Protection    Protection   
3    3   
4    5   
No Communication    No Communication   
Open wire detection
Over-current (OCP)
Over-temperature (OT)
Over-voltage (OV)
Short-circuit Discharge (SCD)
Under-temperature (UT)
Under-voltage (UV)   
Open wire detection
Over-current (OCP)
Over-temperature (OT)
Over-voltage (OV)
Short-circuit Discharge (SCD)
Under-temperature (UT)
Under-voltage (UV)   
Coulomb counter (integrating current sense)
Low-Side NCH CHG/DSG FET Drive
Programmable EEPROM or EPROM
Stackable (built-in interface)
Temperature sense   
Coulomb counter (integrating current sense)
Low-Side NCH CHG/DSG FET Drive
Programmable EEPROM or EPROM
Stackable (built-in interface)
Temperature sense   
6    6   
25    25   
Catalog    Catalog   
20TSSOP    20TSSOP