Design Article
Charging high capacity batteries from 5V sources
David Simmons, Linear Technology Corp.
11/6/2012 10:30 AM EST
Robust in the face of non-ideal sources
The LTC4155 features automatic reduction of input current when the input voltage begins to drop to an unacceptable level. At high charge current levels, this can happen when connections are made through undersized wire, to an undersized adapter, through connectors with mild corrosion, or any number of conditions outside the usual design envelope.
Without intervention, the input voltage to the IC would continue to drop, eventually falling below the undervoltage lockout threshold. The IC would then shut down, allowing the input voltage to recover and restart the whole cycle. The LTC4155 makes the best of a bad situation. As the input voltage falls to 4.3V, the LTC4155 smoothly reduces its input power by whatever amount is necessary to prevent further decay of the input voltage. In this mode the current delivered to the system load and battery is less than the programmed amount, but more than would be available if the input voltage oscillation were allowed to continue. Additionally, the LTC4155 produces an I2C status report and optional interrupt signal to alert the system that corrective or diagnostic action may need to be undertaken by the end user to restore maximum charge current capability.
Conclusion
Combining high current capability with a small monolithic PCB footprint, the LTC4155 is suitable for portable devices with large lithium batteries where board space is at a premium, and heat and charge time are the enemy. USB-compatible input current limit settings further extend versatility to allow opportunistic charging from ubiquitous but lower power sources. Extensive telemetry allows for custom behavior based on changing environmental or application conditions without compromising autonomous battery safety. Uninterrupted power is delivered to the system rail despite common problems such as a deeply discharged battery or a resistive undersized input power cable. The LTC4155 is available in a 28-lead 4mm × 5mm QFN package.
See related links:
Battery Management Systems for Large Lithium-Ion Battery Packs (Part 1 of 3)
Battery Management Systems for Large Lithium-Ion Battery Packs (Part 2 of 3)
Battery Management Systems for Large Lithium-Ion Battery Packs (Part 3 of 3)
Energy harvesting & battery pack protection from shunt charger IC systems
Risk management in batteries for medical (and other) applications
If you found this article to be of interest, visit SmartEnergy Designline where you will find the latest and greatest design, technology, product, and news articles with regard to all aspects of clean technologies. And, to register to our weekly newsletter, click here.
The LTC4155 features automatic reduction of input current when the input voltage begins to drop to an unacceptable level. At high charge current levels, this can happen when connections are made through undersized wire, to an undersized adapter, through connectors with mild corrosion, or any number of conditions outside the usual design envelope.
Without intervention, the input voltage to the IC would continue to drop, eventually falling below the undervoltage lockout threshold. The IC would then shut down, allowing the input voltage to recover and restart the whole cycle. The LTC4155 makes the best of a bad situation. As the input voltage falls to 4.3V, the LTC4155 smoothly reduces its input power by whatever amount is necessary to prevent further decay of the input voltage. In this mode the current delivered to the system load and battery is less than the programmed amount, but more than would be available if the input voltage oscillation were allowed to continue. Additionally, the LTC4155 produces an I2C status report and optional interrupt signal to alert the system that corrective or diagnostic action may need to be undertaken by the end user to restore maximum charge current capability.
Conclusion
Combining high current capability with a small monolithic PCB footprint, the LTC4155 is suitable for portable devices with large lithium batteries where board space is at a premium, and heat and charge time are the enemy. USB-compatible input current limit settings further extend versatility to allow opportunistic charging from ubiquitous but lower power sources. Extensive telemetry allows for custom behavior based on changing environmental or application conditions without compromising autonomous battery safety. Uninterrupted power is delivered to the system rail despite common problems such as a deeply discharged battery or a resistive undersized input power cable. The LTC4155 is available in a 28-lead 4mm × 5mm QFN package.
See related links:
Battery Management Systems for Large Lithium-Ion Battery Packs (Part 1 of 3)
Battery Management Systems for Large Lithium-Ion Battery Packs (Part 2 of 3)
Battery Management Systems for Large Lithium-Ion Battery Packs (Part 3 of 3)
Energy harvesting & battery pack protection from shunt charger IC systems
Risk management in batteries for medical (and other) applications
If you found this article to be of interest, visit SmartEnergy Designline where you will find the latest and greatest design, technology, product, and news articles with regard to all aspects of clean technologies. And, to register to our weekly newsletter, click here.
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