The LTC4015 is a highly integrated, high voltage, multi-chemistry synchronous step-down battery charger controller with onboard telemetry functions. The device efficiently supplies power from an input source such as a wall adapter or solar panel to a Li-Ion/Polymer, lithium-iron-phosphate, or lead acid battery. It provides advanced system monitoring and management functionality, including battery coulomb counting and health monitoring. While a host microcontroller is required to access the most advanced features of the LTC4015, the use of an I²C port is optional. The main charging features of the product can be adjusted using pin-strap configurations and programming resistors. It offers precision ±2% charge current regulation up to 20A, ±1.25% charge voltage regulation, and operation over a 4.5V to 35V input voltage range. The LTC4015 contains an accurate 14-bit analog-to-digital converter (ADC) as well as a high precision coulomb counter. The ADC continuously monitors numerous system parameters, including input voltage, input current, battery voltage, battery current, and reports battery temperature and battery series resistance (BSR) on command. By monitoring these parameters, the LTC4015 can report on the state of health of the battery, as well as its state of charge. All system parameters can be monitored via a two-wire I²C interface, while programmable and maskable alerts ensure that only the information of interest causes an interrupt. The onboard charging profiles are optimized for each of a variety of battery chemistries. Configuration pins allow the user to select between several predefined charge algorithms for each battery chemistry, as well as several algorithms whose parameters can be adjusted via I²C. Both charge voltage and charge current can be automatically adjusted, based on battery temperature to comply with JEITA guidelines, as well as custom settings. The LTC4015 is housed in a 5mm x 7mm QFN package with an exposed metal pad for excellent thermal performance. E- and I-grade devices are guaranteed for operation from –40°C to 125°C. Applications include portable medical instruments, military equipment, battery back-up applications, industrial handhelds, industrial lighting, ruggedized notebooks/tablet computers, and remote powered communication and telemetry systems.