High Voltage 2A Battery Charger Matches Solar Cell Peak Power Tracking with Simple Control Loop

Jun 8 2010 -MILPITAS, CA
  • Linear Technology Corporation introduces the LT3652HV, a higher voltage version of the innovative LT3652 monolithic buck battery charger for modern battery chemistries. The LT3652HV offers a wider battery float voltage range than the LT3652 — up to 18V — and features the same input voltage regulation loop that controls charge current to hold the input voltage at a programmed level. The LT3652HV has the flexibility to charge many different battery configurations from various input supplies, and when it is connected to a solar panel, the input regulation loop maintains the panel at peak output power.

    According to Steve Pietkiewicz, Vice President and General Manager of Power Products, “The LT3652HV, with its increased output voltage capability, is a welcome addition to our growing line of solar input compatible battery charger ICs. Like the LT3652, its simple but unique input voltage regulation loop circuitry delivers virtually the same charging efficiency as more complex and expensive Maximum Peak Power Tracking (MPPT) techniques.”

    The LT3652HV accepts a wide range of inputs from 4.95V to 34V with a 40V absolute maximum rating for added system margin. The input voltage regulation loop also allows optimized charging from poorly regulated sources where the input can collapse under overcurrent conditions. It charges a variety of battery pack configurations, including 1 to 4 Li-Ion/Polymer cells in series, 1 to 5 LiFePO4 (Lithium Iron Phosphate) cells in series and sealed lead acid (SLA) batteries up to 18V. Applications include solar-powered systems, 12V to 24V automotive equipment and battery chargers.

    The LT3652HV's charge current is programmable up to 2A. This stand-alone battery charger requires no external microcontroller and features user-selectable termination, including C/10 or an on-board timer. The device's 1MHz fixed switching frequency enables small solution sizes. Float voltage feedback accuracy is specified at ±0.5%, charge current accuracy is ±5% and C/10 detection accuracy is ±2.5%. Once charging is terminated, the LT3652HV automatically enters a low current standby mode, which reduces the input supply current to 85µA. In shutdown, the input bias current is reduced to 15µA. For autonomous charge control, an auto-recharge feature starts a new charging cycle if the battery voltage falls 2.5% below the programmed float voltage.

    The LT3652HV is available in thermally enhanced packages: a low-profile (0.75mm) 12-pin 3mm × 3mm DFN package, and a 12-lead MSOP package. Both are available in E- and I- grade versions, guaranteed from –40ºC to 125ºC. Pricing starts at $3.40 and $3.70 each, respectively in 1,000-piece quantities. For more information, visit www.linear.com/product/LTC3652HV.

    Summary Features LT3652HV

    • Solar Power Supply Voltage Regulation Loop for Peak Tracking in Solar Applications
    • Wide Input Voltage Range: 4.95V to 34V (40V Absolute Maximum Rated)
    • Programmable Charge Current up to 2A
    • Multi-Chemistry: Resistor Programmable Float Voltage Up to 18V Accommodates Li-Ion/Polymer (1 to 4 cell), LiFePO4 (1 to 5 cell) and SLA Chemistries
    • User-Selectable Termination: C/10 or On-board Termination Timer
    • Draws <1µA from the Battery During Non-Charging Periods
    • 1MHz Switching Frequency Enables Small External Components
    • ±0.5% Float Voltage Feedback Reference Accuracy
    • ±5% Charge Current Accuracy
    • NTC Resistor Temperature Monitor
    • Bad Battery Detection with Auto-Reset
    • Low-Profile (0.75mm) 3mm × 3mm DFN-12 Package & MSOP-12E Package

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