Path Switching Without Requiring Backup Supply Voltage Lower Than Primary Supply Voltage

Analog Devices announced the launch of LTC4418, a new dual-input power prioritizer for 2.5V to 40V systems that sets power supply priority.

Electronic systems utilize batteries and capacitors for backup power to enable portability, preserve memory during brownout conditions, and ensure proper shutdown during power loss.

The LTC4418 typically supplies power to the load using a primary power supply such as an adapter or main battery, but switches to a backup power supply—typically a battery or expensive capacitor—when a voltage drop or power loss occurs in the primary supply. Operating up to a maximum of 40V, the LTC4418 can handle various types of power sources including adapters, USB ports, supercapacitors, as well as multi-cell lead-acid batteries, lithium-ion, or NiMH batteries.

The LTC4418 has low standby quiescent current consumption of 26μA and supports shutdown mode, making it ideal for battery-powered portable systems. Unlike diode-based solutions, the backup supply voltage does not need to be lower than the primary supply voltage. When the primary supply exceeds precisely set under-voltage and over-voltage thresholds, an external back-to-back P-channel MOSFET switch transfers the power path from the primary supply to the backup power supply.

When there are two or more power supplies, priority can be set by cascading the LTC4418 with a three-input power LTC4417.