BQ77PL900_2 Datasheet, PDF (1/60 Pages) Texas Instruments – Five to Ten Series Cell Lithium-Ion or Lifthium-Polymer Battery Protector and Analog Front End

bq77PL900
www.ti.com ...................................................................................................................................................... SLUS844B – JUNE 2008 – REVISED JANUARY 2009
Five to Ten Series Cell Lithium-Ion or Lithium-Polymer Battery Protector
and Analog Front End
FEATURES
1
• 5, 6, 7, 8, 9, or 10 Series-Cell Primary
Protection
• PMOS FET Drive for Charge and Discharge
FETs
• Capable of Operation with 1-mΩ Sense
Resistor
• Supply Voltage Range from 7 V to 50 V
• Low Supply Current of 450 µA Typical
• Integrated 5-V, 25-mA LDO
• Integrated 3.3-V, 25-mA LDO
• Stand-Alone Mode
– Pack Protection Control and Recovery
– Individual Cell Monitoring
– Integrated Cell Balancing
– Programmable Threshold and Delay Time
for
– Overvoltage
– Undervoltage
– Overcurrent in Discharge
– Short Circuit in Discharge
– Fixed Overtemperature Protection
• Host Control Mode
– I²C Interface to Host Controller
– Analog Interface for Host Cell Measurement
and System Charge/Discharge Current
– Host-Controlled Protection Recovery
– Host-Controlled Cell Balancing
APPLICATIONS
• Cordless Power Tools
• Power Assisted Bicycle/Scooter
• Uninterruptible Power Supply (UPS) Systems
• Medical Equipment
• Portable Test Equipment
DESCRIPTION
The bq77PL900 is a five to ten series cell lithium-ion
battery pack protector. The integrated I²C
communications interface allows the bq77PL900 also
to be as an analog front end (AFE) for a Host
controller. Two LDOs, one 5-V, 25-mA and one 3.3-V,
25-mA, are also included and may be used to power
a host controller or support circuitry.
The bq77PL900 integrates a voltage translation
system to extract battery parameters such as
individual cell voltages and charge/discharge current.
Variables such as voltage protection thresholds and
detection delay times can be programmed by using
the internal EEPROM.
The bq77PL900 can act as a stand-alone
self-contained battery protection system (stand-alone
mode). It can alternatively be combined with a host
microcontroller to offer fuel gauge or other battery
management capabilities to the host system
(host-control mode).
The bq77PL900 provides full safety protection for
overvoltage, undervoltage, overcurrent in discharge,
and short circuit in discharge conditions. When the
EEPROM programmable safety thresholds are
reached, the bq77PL900 turns off the FET drive
autonomously. No external components are needed
to configure the protection features.
The analog front end (AFE) outputs allow a host
controller to observe individual cell voltages and
charge/discharge currents. The host controller’s
analog-to-digital converter connects to the
bq77PL900 to acquire these values.
Cell balancing can be performed autonomously, or
the host controller can activate it individually via a cell
bypass path integrated into the bq77PL900. Internal
control registers accessible via the I²C interface
configure this operation. The maximum balancing
bypass current is set via an external series resistor
and the internal FET-on resistance (typically 400 Ω).
Optionally, external bypass cell balance FETs can be
used for increased current capability.
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2008–2009, Texas Instruments Incorporated