Datasheet

FEATURE SET
Primary (First-Level) Safety Features
Secondary (Second-Level) Safety Features
Charge Control Features
Gas Gauging
Display Types
bq78PL114
SLUS850B – SEPTEMBER 2008 – REVISED APRIL 2009 ................................................................................................................................................ www.ti.com
The bq78PL114 implements a breadth of system protection features which are easily configured by the
customer. First-level protections work by controlling the MOSFET switches. These include:
• Battery cell over/undervoltage protection
• Pack over/undervoltage protection
• Charge and discharge overcurrent protection
• Short-circuit protection
• External MOSFET control inputs (EFCIx) with programmable polarity
• Up to 12 external temperature inputs for accurate cell and MOSFET monitoring
• Watchdog timer protection
• Brownout detection and protection against extreme pack undervoltage
The bq78PL114 can detect more serious system faults and activate the SPROT pin, which can be used to open
an in-line chemical fuse to permanently disable the pack. Secondary optional features include
• Fully independent of first-level protections
• SmartSafety algorithms for early detection of potential faults
– Temperature abnormalities (variances, extremes, rate of change, etc.)
– Disconnected cell voltage inputs
– Cell imbalance exceeds safety limits
– Impedance rise due to cell or weld strap fault
• MOSFET failure or loss of MOSFET control
• Safety overvoltage, pack and cell
• Safety overtemperature, limits for both charge and discharge
• Safety overcurrent, charge and discharge
• Failed current measurement, voltage measurement, or temperature measurement
• Meets SMBus 2.0 and Smart Battery System (SBS) Specification 1.1 requirements
• Active cell balancing using patented PowerPump technology, which eliminates unrecoverable capacity loss
due to normal cell imbalance
• Balancing-current monitoring to detect cell problems
• Simultaneous, synchronous measurement of all cell voltages in a pack
• Simultaneous, synchronous measurement of pack current with cell voltages
• Reports target charging current and/or voltage to an SBS Smart Charger
• Reports the chemical state-of-charge for each cell and pack
• Supports precharging and zero-volt charging with separate MOSFET control
• Programmable, Chemistry-specific parameters
• Fault reporting
• The bq78PL114 accurately reports battery cell and pack state-of-charge (SOC). No full charge/discharge
cycle is required for accurate reporting.
• State-of-charge is reported via SMBus and optional display.
• 18-bit integrating delta-sigma ADC coulomb counter, with programmable snap-to-zero value
• The bq78PL114 drives a three- to five-segment LED display in response to a pushbutton (LEDEN) input
signal. Each LED pin can sink up to 10 mA.
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