bq77PL900
www.ti.com ........................................................................................................................................................ SLUS844A–JUNE 2008–REVISED AUGUST 2008
Five to Ten Series Cell Lithium-Ion or Lithium-Polymer Battery Protector
and Analog Front End
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FEATURES
DESCRIPTION
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5, 6, 7, 8, 9, or 10 Series-Cell Primary
Protection
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.
PMOS FET Drive for Charge and Discharge
FETs
Capable of Operation with 1-mΩ Sense
Resistor
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Supply Voltage Range from 7 V to 50 V
Low Supply Current of 450 µA Typical
Integrated 5 V 25-mA LDO
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.
Integrated 3.3 V 25-mA LDO
Stand-Alone Mode
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Pack Protection Control and Recovery
Individual Cell Monitoring
The bq77PL900 can act as
a
stand-alone
Integrated Cell Balancing
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).
Programmable Threshold and Delay Time
for
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Overvoltage
Undervoltage
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.
Overcurrent in Discharge
Short Circuit in Discharge
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Fixed Overtemperature Protection
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Host Control Mode
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I2C Interface to Host Controller
Analog Interface for Host Cell Measurement
and System Charge/Discharge Current
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
bq77PL900 to acquire these values.
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Host-Controlled Protection Recovery
Host-Controlled Cell Balancing
converter
connects
to
the
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.
APPLICATIONS
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Cordless Power Tools
Power Assisted Bicycle/Scooter
Uninterruptible Power Supply (UPS) Systems
Medical Equipment
Portable Test Equipment
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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, Texas Instruments Incorporated