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Linear Technology Introduces a New 4A Multi-Cell Fast-Charge Battery Charge Controller

High-Efficiency switch-mode controller is ideal for a wide range of Battery Chemistry's with Fast-Charge Capability

Linear Technology has released the LTC4009, a fast-charge 4A capable, high efficiency switchmode battery charger controller for multiple battery chemistries which minimizes power dissipation without compromising board space. The LTC4009 supports Li-Ion/Polymer, NiMH, NiCd and sealed lead acid battery chemistries in multi-cell configurations. AC adapter current limiting maximizes the charge rate for a given fixed input power level, allowing the end product to operate at the same time the battery is charging without complex load management algorithms. The IC operates from input voltages up to 28V and is intended for applications including portable computers, portable instruments, and battery backup systems.

The LTC4009's synchronously rectified, buck switching topology drives all n-channel MOSFETs and enables efficiencies as high as 90% at 4A. Final float voltage accuracy is specified at ±0.5% and charge current is programmable with accuracy of ±4%. The LTC4009's quasi-constant frequency PWM architecture guarantees no audible noise operation and minimizes filtering needs, while the high operating frequency of 550kHz allows the use of small inductors and capacitors. Improved non-overlap control keeps efficiency high as external power FET turn on/off times may vary with temperature and supplier.

The LTC4009 consumes <20uA in shutdown, increasing battery run time in portable applications. For safety and autonomous charge control, the IC includes battery float voltage over-voltage protection, reverse charge current protection, charge current monitoring, soft start, ac adapter present indication, and current limit indication.

Features of the LTC4009 include:

  • High Efficiency PWM Switchmode Battery Charger Controller
  • Multiple Battery Chemistries & Multi-Cell Configurations Supported: Li-Ion/Polymer, NiMH, NiCd, SLA
  • Charge Current up to 4A
  • 550kHz Switching Frequency Enables Small External Components
  • ±0.5% Output Float Voltage Accuracy
  • Programmable Charge Current: ±4% Accuracy
  • No Audible Noise with Ceramic Capacitors
  • Synchronous Rectification: High Efficiency up to 92% @ 2A
  • Enhanced Non-Overlap Control of External Power FETs
  • Wide Input Supply Voltage Range: 6V to 28V
  • Wide Output Battery Voltage Range: 3V to 28V
  • Indicator Outputs for AC Adapter Present, Charging, C/10 Current Detection and Input Current Limiting
  • Analog Charge Current Monitor
  • Micropower Shutdown
  • Compact, Low-Profile (0.75mm) 4mm x 4mm QFN-20 Package

The company's Web site address is www.analog.com.
[Reprinted with kind permission from Linear Technology]