Versatile buck-boost battery charging controller

6th November 2013
Nat Bowers

Linear Technology has today announced a new advanced high voltage power manager and multi-chemistry battery charger, the LTC4020. Designed to efficiently transfer power from a variety of sources to a system power supply rail and a battery, the LTC4020 offers precision charge current regulation and ±0.5% charge voltage regulation.

Operating across a wide 4.5V to 55V input voltage range, the LTC4020 is compatible with a variety of different input voltage sources. This wide output voltage range up to 55V and three selectable termination algorithms enable the LTC4020 to accommodate an equally wide variety of battery stack voltages and chemistries. Incorporating a step-up/step-down DC-DC controller, the LTC4020 enables operation with battery voltages that are above, below or equal to the input voltage. Guaranteed to operate over a wide temperature range of -40°C to 125°C, typical applications for the LTC4020 include portable industrial and medical equipment, solar-powered systems, military communications equipment, and 12V to 24V embedded automotive systems.

The integrated intelligent PowerPath topology reduces the voltage range required by downstream system components to that of the expected battery voltage range rather than the full extent of the input voltage source. Instant-on operation still ensures system load power with a fully discharged battery. The PowerPath topology also preferentially provides power to the system load when input power is limited. This means that the LTC4020's ideal diode controller guarantees that ample power is always available to VOUT if there is insufficient power available from the DC-DC converter. With an input voltage regulation loop, a maximum power point control circuit manages charge current to hold the input voltage at a programmed level, ideal for high impedance input or solar panel-powered applications. When no input supply is present, the battery drain current is reduced to only 10µA, maintaining maximum stored capacity.

With three pin-selectable charging profiles optimised for a variety of battery chemistries, the LTC4020 offers a constant-current/constant-voltage charge characteristic with either C/10 or timed termination for use with lithium-based battery systems including Li-Ion, Li-polymer and LiFePO4. Charging of supercapacitors or the trickle charging of nickel-based batteries is possible thanks to a constant-current characteristic with timed termination. A 4-step, 3-stage lead-acid charge profile works well with all types of lead-acid batteries including sealed, AGM and flooded. Two digital open-drain outputs provide charger status and signal fault conditions including battery charging, standby or shutdown modes, battery temperature faults and bad battery faults. Other features of the battery charger include: temperature-qualified charging using an NTC thermistor, automatic recharge and precondition low current charging for deeply discharged cells.

Available now in a low profile (0.75mm) 38-pin 5mm x 7mm QFN package with a backside metal pad for excellent thermal performance, the LTC4020 is priced at $4.95 (USD) each in 1,000-piece quantities.

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