LT3652 2 A Battery Charger for Solar Power

Analog Devices' 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