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.