1 Features
1• 2-Series Cell Secondary Protection
• Automatic Cell Imbalance Correction with External
Enable Control
– ±30-mV Enable, 0-mV Disable Thresholds
Typical
• External Capacitor-Controlled Delay Timer
• External Resistor-Controlled Cell Balance Current
• Low Power Consumption ICC < 3 μA Typical
(VCELL(ALL) < VPROTECT)
• Internal Cell Balancing Handles Current
up to 15 mA
• External Cell Balancing Mode Supported
• High-Accuracy Overvoltage Protection:
– ±25 mV with TA = 0°C to 60°C
• Fixed Overvoltage Protection Thresholds:
4.30 V, 4.35 V
• Small 8L DRB Package

2 Applications
• 2nd Level Protection in Li-Ion Battery Packs
– Netbook Computers
– Power Tools
– Portable Equipment and Instrumentation
– Battery Backup Systems

3 Description
The bq2920x device is a secondary overvoltage
protection IC for 2-series cell lithium-ion battery packs
that incorporates a high-accuracy precision
overvoltage detection circuit and automatic cell
imbalance correction.
The voltage of each cell in a 2-series cell battery
pack is compared to a factory programmed internal
reference voltage. If either cell reaches an
overvoltage condition, the OUT pin changes from low
to high state.
The bq2920x can perform automatic voltage-based
cell imbalance correction. Balancing can start when
the cell voltages are different by nominally 30 mV or
more and stops when the difference is nominally 0
mV. Cell balancing is enabled and disabled by the
CB_EN pin.