Linear Technology introduces the LT3652, an innovative, solar power directed monolithic buck battery charger IC for modern battery chemistries that operates over a 4.95V to 32V input voltage range. The LT3652 provides a constant-current/constant-voltage charge characteristic, with maximum charge current externally programmable up to 2A. 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 3.3V float voltage feedback reference, so any desired battery float voltage up to 14.4V can be programmed with a resistor divider.
The LT3652 accepts a wide range of inputs from 4.95V to 32V 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 over-current 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 14.4V. Applications include solar powered systems, 12V to 24V automotive equipment and battery chargers.
The LT3652’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 onboard 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 LT3652 automatically enters a low current standby mode, which reduces the input supply current to 85uA. In shutdown, the input bias current is reduced to 15uA. 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: 4.95V to 32V (40V Abs Max)
- Programmable charge rate up to 2A
- User selectable termination: C/10 or on-board termination timer
- Resistor programmable float voltage up to 14.4V accommodates Li-ion/polymer, LiFePO4, SLA, NiMH/NiCd chemistries
- 1MHz fixed frequency
- 0.5% float voltage reference accuracy
- 5% charge current accuracy
- 2.5% C/10 detection accuracy
- Binary-coded open-collector status pins
- 3mm × 3mm DFN12 package
- No Vin blocking diode required for battery voltages ≤ 4.2V