LT3652 2 A Battery Charger for Solar Power

By Analog Devices Inc 109

LT3652 2 A Battery Charger for Solar Power

LTC's LT3652 is a solar power directed monolithic buck battery charger IC for modern battery chemistries whichoperates over a 4.95 V to 32 V input voltage range. The LT3652 provides a constant-current/constant-voltage charge characteristic with maximum charge current externally programmable up to 2 A. The LT3652 features an innovative input voltage regulation loop, which controls charge current to hold the input voltage at a programmed level. The charger employs a 3.3 V float voltage feedback reference so any desired battery float voltage up to 14.4 V can be programmed with a resistor divider.

The LT3652 accepts a wide range of inputs from 4.95 V to 32 V with a 40 V 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 3 Li-Ion / polymer cells in series, 1 to 4 LiFePO4 (lithium iron phosphate) cells in series, and sealed lead acid (SLA) batteries up to 14.4 V. Applications include solar powered systems, 12 V to 24 V automotive equipment, and battery chargers.

The LT3652’s charge current is programmable up to 2 A. This stand-alone battery charger requires no external microcontroller and features user-selectable termination including C/10 or an onboard timer. The device’s 1 MHz 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 LT3652 automatically enters a low current standby mode, which reduces the input supply current to 85 µA. In shutdown, the input bias current is reduced to 15 µA. 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. Diagram

  • Input supply voltage regulation loop for peak power tracking in (MPPT) solar applications
  • Wide input voltage range: 4.95 V to 32 V (40 V abs max)
  • Programmable charge rate up to 2 A
  • User selectable termination: C/10 or on-board termination timer
  • Resistor programmable float voltage up to 14.4 V accommodates Li-ion / polymer, LiFePO4, SLA, NiMH / NiCd chemistries
  • 1 MHz fixed frequency
  • 0.5% float voltage reference accuracy
  • 5% charge current accuracy
  • 2.5% C/10 detection accuracy
  • Binary-coded open-collector status pins
  • 3 mm × 3 mm DFN12 package
  • No VIN blocking diode required for battery voltages ≤ 4.2 V
  • Solar power/trickle charging
  • Remote monitoring stations
  • Portable hand-held instruments
  • Battery-powered applications
  • 12 V to 24 V automotive systems
  • LiFePO4 (lithium iron phosphate) applications