FEATURES
· 2-, 3-, or 4-Cell Secondary Protection
· Low Power Consumption ICC < 2 μA
[VCELL(ALL) < V(PROTECT)]
· High Accuracy Over Sense Voltage:
– bq29400: 4.35 V ±25 mV
– bq29400A: 4.40 V ±25 mV
– bq29401: 4.45 V ±25 mV
– bq29405: 4.65 V ±25 mV
· Prefixed Protection Threshold Voltage
· Programmable Delay Time
· High Power Supply Ripple Rejection
· Stable During Pulse Charge Operation

APPLICATIONS
· 2nd Level Protection in Lion Battery Packs in
– Notebook PCs
– Portable Instrumentation
– Medical and Test Equipment

DESCRIPTION
The bq29400, bq29400A, bq29401, and bq29405 are
BiCMOS secondary protection ICs for 2-, 3-, or 4-cell
Lithium-Ion battery packs that incorporate a
high-accuracy precision over voltage detection circuit.
They include a programmable delay circuit for over
voltage detection time.

FUNCTION
Each cell in a multiple cell pack is compared to an
internal reference voltage. If one cell reaches an
overvoltage condition, the protection sequence
begins. The bq2940x device starts charging an external capacitor through the CD pin. When the CD
pin voltage reaches 1.2 V, the OUT pin changes from
a low level to a high level.