FEATURES
3- or 4-Cell Series Protection Control
Autonomous Overcurrent and Short Circuit
Protection
Provides Individual Cell Voltages to Battery
Management Host
Integrated Cell Balancing Control
I2C Compatible User Interface Allows Access
to Battery Information
User Control to Initiate Protection
Integrated 3.3-V 25-mA LDO
Programmable Shutdown and Brownout
Control
Provides Drive for Three External FETs
Low Supply Current of 140 μA Typical
Programmable Threshold and Delay for
Short-Circuit Current Protection
Provides Drive for Three External FETs
Can Directly Interface With bq2083/5 for
Complete Battery Management Solution

APPLICATIONS
Notebook Computer Battery Packs
Test Equipment

DESCRIPTION
The bq29311 is a three- or four-cell lithium-ion battery
pack protection analog front end (AFE) IC that
incorporates a 3.3-V 25-mA low-dropout regulator
(LDO) and an I2C compatible interface to extract battery
parameters such as cell voltages and control output
status. Other parameters, such as overcurrent
protection threshold and delay, can also be
programmed into the bq29311 to increase the flexibility
of the battery management system.
The bq29311 provides safety protection in overcurrent,
short circuit, overvoltage, and undervoltage conditions
via control from the battery management host. In
overcurrent and short-circuit conditions the bq29311
can directly activate the FET drive as a secondary
protection level. The communications interface allows
the host to control and observe the current status of the
protection, to set overcurrent and overload levels, to set
the overcurrent and overload blanking delay time,
short-circuit threshold levels, and short-circuit blanking
delay time, and to program for the VREG shutdown
voltage and brownout-detection thresholds.
Each cell is balanced by a discharge path, which is
enabled by the internal control registers accessible
through the I2C compatible interface. The maximum
current is set by an external series resistor with an
absolute maximum value of 10 mA discharge current
per cell.