55VIN/55VOUT buck-boost battery charging controller offers multi-chemistry benefits
The LTC4020 offers precision charge current regulation, ±0.5% charge voltage regulation and operates across a wide 4.5 V to 55 V input voltage range compatible with a variety of different input voltage sources. With an output voltage range up to 55 V and three selectable termination algorithms, the LTC4020 accommodates an equally wide variety of battery stack voltages and chemistries. The LTC4020 contains a step-up/step-down DC/DC controller, enabling operation with battery voltages that are above, below or equal to the input voltage (VIN). Typical applications include portable industrial and medical equipment, solar-powered systems, military communications equipment, plus 12 V to 24 V embedded automotive systems.
The LTC4020 features an intelligent PowerPath topology that 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. However, instant-on operation still ensures system load power with a fully discharged battery. The topology preferentially provides power to the system load when input power is limited – the device’s ideal diode controller guarantees that ample power is always available to VOUT if there is insufficient power available from the DC/DC converter. A maximum power point control (MPPC) circuit features an input voltage regulation loop, which controls 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 10 µA, maintaining maximum stored capacity.
The LTC4020’s three pin-selectable charging profiles are optimized for a variety of battery chemistries. The LTC4020 can provide a constant-current/constant-voltage (CC/CV) charge characteristic with either C/10 or timed termination for use with lithium-based battery systems including Li-Ion, Li-polymer and LiFePO4. A constant-current (CC) characteristic with timed termination can be used for charging supercapacitors or trickle charging nickel-based batteries.
A 4-step, 3-stage lead-acid charge profile works well with all types of lead-acid batteries including sealed, AGM and flooded. An integrated timer controls termination during CC/CV charging, as well as additional protection during battery preconditioning and absorption charging for lead-acid batteries. Two digital open-drain outputs provide charger status and signal fault conditions. These binary coded pins signal 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.
Availability and Pricing
The LTC4020 is housed in a low profile (0.75 mm) 38-pin 5 mm x 7 mm QFN package with a backside metal pad for excellent thermal performance. The device is guaranteed for operation from -40°C to 125°C. 1,000-piece pricing starts at $4.95 each.
More information about the LTC4020 battery charger at
www.linear.com/product/LTC4020
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