1FEATURES
· 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 mA 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.