• Safe Management of Fast Charge for NiCd, NiMH, or Li-Ion Battery Packs
• High-Frequency Switching Controller for Efficient and Simple Charger Design
• Pre-Charge Qualification for Detecting Shorted, Damaged, or Overheated Cells
• Fast-Charge Termination by ΔT/Δt for Nickel Chemistries, Minimum Current for Li-Ion Chemistries, Maximum Temperature, and Maximum Charge Time
• Selectable Top-Off Mode for Achieving Maximum Capacity in NiMH Batteries
• Programmable Trickle-Charge Mode for Reviving Deeply Discharged Batteries and for Postcharge Maintenance
• Built-in Battery Removal and Insertion Detection
• Sleep Mode for Low Power Consumption
• APPLICATIONS
  • Multi-Chemistry Charger
  • Nickel Charger
  • High-Power, Multi-Cell Charger

GENERAL 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 chooses the proper battery chemistry (either nickel or lithium) and proceeds with the optimal charging and termination algorithms. This process eliminates undesirable, undercharged, or overcharged conditions, and allows accurate and safe termination of fast charge.

Depending on the chemistry, the bq2000T provides a number of charge termination criteria:

• Rate of temperature rise (ΔT/Δt) (for NiCd and NiMH)
• Minimum charge current (for Li-Ion)
• Maximum temperature
• Maximum charge time

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, the bq2000T provides an optional top-off charge to maximize the battery capacity.

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