Datasheet

Lifetime Logging (Readable via SMBus)
Forensic Data Logging (Readable via SMBus)
Power Modes
OPERATION
bq78PL114
www.ti.com ................................................................................................................................................ SLUS850B – SEPTEMBER 2008 – REVISED APRIL 2009
• The bq78PL114S12 drives a three- to five-segment static liquid-crystal display.
• The bq78PL114S12 drives a three- to five-segment electronic paper display. An external 15-V voltage source
is required. E Ink Corporation supplies this type of display.
The display type is selected via the parameter set.
• Recording of faults, events, anomalies, minimum and maximum values
• Maximum/minimum temperature
• Maximum/minimum pack voltage
• Maximum/minimum cell voltage in a pack
• 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
• Last 10 failures causing first-level safety action
• Forensic data up-loadable to host CPU via SMBus
• 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 command is issued. Exit occurs when the
SMBus 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 programmable between 2.3 V and 2.7 V, with 2.5 V being typical.
OVERCURRENT
STATE ENTRY CONDITION EXIT CONDITION
PROTECTION
Normal operation as determined by firmware Firmware directed to the following operating
Active Fully active
modes
No load current flowing for predetermined
Standby Fully active Load activity
time
Ship Not active Protected SMBus command SMBus becomes active
Extreme cell Not active (precharge Vcell charge above ECUV recovery threshold
Enabled when Vcell < ECUV
undervoltage enabled) (2.7 V/cell typical)
The bq78PL114 battery-management controller serves as a master controller for a Li-Ion battery system
consisting of up to 8 cells in series. The bq78PL114S12 firmware upgrade supports up to 12 cells in series. Any
number of cells 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 in battery management. Temperature is
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Product Folder Link(s): bq78PL114