The LTC4091 is a 36V Li-Ion battery charger and power backup manager. The integrated step-down switching regulator charges a battery from a primary power source while providing power to the load. If primary power is lost, the load is seamlessly transitioned to the backup Li-ion/polymer battery. To protect sensitive downstream loads, the maximum output voltage is 4.45V.The LTC4091 provides an adaptive output that tracks the battery voltage for high efficiency charging. The charge current is programmable and an end-of-charge status output (CHRG) indicates full charge. Also featured is a termination timer and an NTC thermistor input used to monitor battery temperature while charging.During backup, an internal 75mΩ ideal diode connects the battery to the load. An optional external ideal diode FET driver is available to reduce the voltage drop even further. 4.1V or 4.2V battery charge voltages can be selected.ApplicationsFleet and Asset TrackingAutomotive GPS Data LoggersAutomotive Telematics SystemsBattery Backup Systems