Lifetime Data Logging (Readable via SMBus or SPI)

Forensic Data Logging (Readable via SMBus or SPI)

Power Modes

OPERATION

bq78PL114

• Recording of faults, events, anomalies, minimum and maximum values

• Maximum/minimum temperature

• Maximum/minimum pack voltage

• Maximum/minimum cell voltages

• Maximum charge and discharge currents

• Last known full capacity of each cell

• Cycle count and/or cumulative number of ampere-hours delivered by the battery

• Battery pack status: being charged, discharged, or at rest

• Balancing effort required by each bank of cells to maintain balance

• Information for each cell bank for period leading up to failure

• Last 10 failures causing first-level safety action

• Forensic data up-loadable to host CPU via SMBus or SPI

• Forensic data recording of anomalies and events

• Normal Mode: The bq78PL114 performs measurements and calculations, makes decisions, and updates

internal data approximately once per second. All safety circuitry is fully functional in this mode.

• Standby Mode: The bq78PL114 performs as in normal mode, but at a dramatically reduced rate to lower

power consumption at times when the host computer is inactive or the battery system is not being used. All

safety circuitry remains fully functional in this mode.

• Ship Mode: The bq78PL114 disables (opens) all the protection MOSFETs, and continues to monitor

temperature and voltage, but at a reduced measurement rate to dramatically lower power consumption.

Environmental data is saved in flash as a part of the historical record. Safety circuitry is disabled in this mode.

The device does not enter this power state as a part of normal operation; it is intended for use after factory

programming and test. Entry occurs only after a unique SMBus or SPI command is issued. Exit occurs when

the SMBus or SPI lines return to an active state.

• Extreme Cell Undervoltage (ECUV) Shutdown Mode: In this mode, the bq78PL114 draws minimal current

and the charge and discharge protection MOSFETs are disabled (opened). The precharge MOSFET remains

enabled when a charge voltage is present. Safety circuitry is disabled in this mode. The device does not enter

this mode as a part of normal operation; it enters this state during extreme cell undervoltage conditions

(ECUV). The ECUV threshold is fully programmable below 2.7V.

CURRENT

OVERCURRENT

STATE

ENTRY CONDITION

EXIT CONDITION

DRAW (Typ)

PROTECTION

Normal operation as determined by

Firmware directed to the following

Active

< 250

µA

Fully active

firmware

operating modes

No load current flowing for

Standby

< 150

µA

Fully active

Load activity

predetermined time

Ship

< 40

µA

Not active

Protected SMBus or SPI command

SMBus or SPI becomes active

Not active

Extreme cell

Vcell charge above ECUV recovery

< 1

µA

(precharge

Enabled when Vcell < ECUV

undervoltage

threshold (2.7 V/cell typical)

enabled)

The bq78PL114 battery management controller serves as the master controller for a Li-Ion battery system

consisting of up to 12 cells in series. Any number may be connected in parallel; other system or safety issues

limit the number of parallel cells. The bq78PL114 provides extraordinarily precise state-of-charge gas gauging

along with first and second level pack safety functions. Voltage and current measurements are performed

synchronously and simultaneously for all cells in the system, allowing a level of precision not previously possible

Copyright © 2008, Texas Instruments Incorporated

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Product Folder Link(s): bq78PL114