bq2000

Features:

*Safe management of fast charge for NiCd, NiMH, or Li-Ionbatterypacks
*High-frequency switching controller for efficient and simple chargerdesign
*Pre-charge qualification fordetecting shorted, damaged, or overheated cells
*Fast-charge termination by peak voltage (PVD), minimum current (Li-Ion), maximum temperature, and maximum chargetime
*Selectable top-off mode for achieving maximum capacity in NiMHbatteries
*Programmable trickle-charge mode for reviving deeply discharged batteries and for postchargemaintenance
*Built-in battery removal and insertiondetection
*Sleep mode for low power consumption


Pinout




Specifications

A negative-coefficient thermistor, referenced to VSS and placed in thermal contact with the battery, may be used
as a temperature-sensing device. Figure 5 shows a typicaltemperature-sensingcircuit.


During fast charge, the bq2000 compares the battery temperature to an internal high-temperature cutoff threshold, V_TCO. As shown in Table 4, high-temperature termination occurs when voltage at pin TS is less than thisthreshold.


Description

The bq2000 is a programmable,monolithic IC for fast-charge management of nickel cadmium (NiCd),nickel metal-hydride (NiMH), or lithium-ion (Li-Ion) batteries in single- or multi-chemistry applications. The bq2000 detects the battery chemistry and proceeds with the optimal charg-
ing and termination algorithms. This process eliminates undesirable under-charged or overcharged conditions and allows accurate and safe termi-
nationoffastcharge.


Depending on the chemistry, the bq2000 provides a number of charge terminationcriteria:
Peak voltage, PVD (for NiCd and NiMH)
Minimum charging current (f or Li-Ion)
Maximumtemperature
Maximumchargetime


For safety, the bq2000 inhibits fast charge until the battery voltage and temperature are within user-defined limits. If the battery voltage is
below the low-voltage threshold, the bq2000 uses trickle-charge to condition the battery. For NiMH batteries, the bq2000 provides an optional top-off charge to maximize thebatterycapacity.


The integrated high-frequency comparator allows the bq2000 to be the basis for a complete, high-efficiency power-conversion circuit for both nickel-based and lithium-based chemistries.