bq2000T

Features:

Safe management of fast charge for NiCd, NiMH, or Li-Ionbatterypacks
 High-frequency switching controller for efficient and simple chargerdesign
Pre-charge qualification for detecting shorted, damaged, or overheated cells
Fast-charge termination by T/t minimum current(Li-Ion), maximum temperature, and maximum charge time
Selectable top-off mode for achieving maximum capacity in NiMHbatteries
Programmable trickle-charge mode for reviving deeply discharged batteries and for post-chargemaintenance
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 typi-caltemperature-sensingcircuit.


During fast charge, the bq2000T compares the battery temperature to an internal high-temperature cutoff threshold, VTCO. As shown in Table 4, high-temperature termination occurs when voltage at pin TS is less than thisthreshold.


Description

The bq2000T 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 bq2000T detects the battery chemistry and proceeds with the optimal charging and termination algorithms.This process eliminates undesirable undercharged or overcharged conditions and allows accurate and safe terminationoffastcharge.


Depending on the chemistry, the bq2000T provides a number of chargeterminationcriteria:
Rate of temperature rise,T/t (for NiCdandNiMH)
Minimum charging current (for Li-Ion)
Maximumtemperature
Maximumchargetime


For safety, the bq2000T 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 bq2000T uses trickle-charge to condition the battery. For NiMH batteries, it provides an optional top-off charge to maximize thebatterycapacity.


The integrated high-frequency comparator allows the bq2000T to be the basis for a complete, high-efficiency power-conversion circuit for both nickel-based and lithium-based chemistries.