Single-chip USB power manager

Replete with PowerPath control, the LTC4085—a monolithic autonomous power manager, diode controller and standalone battery charger—will find homes in a number of portable USB devices. PowerPath control provides power to the USB peripheral device and charges the peripheral's single-cell Li-ion battery from the USB VBUS or a walladapter power supply.

To comply with USB current-limit specifications, Linear Technology's LTC4085 automatically reduces battery-charge current as the system load current increases. To ensure that a fully charged battery remains fresh when the bus is connected, the IC directs power to the load through the USB bus rather than extracting power from the battery. Once the power source is removed, current flows from the battery to the load through an internal 200mΩ low-loss ideal diode, minimising voltage drop and power dissipation. Onboard circuitry drives an optional external PFET hookup to reduce the overall ideal diode impedance below 50mΩ if required by the application.

The LTC4085 is able to detect the presence of a wall adapter and use it as an alternate battery-charging power source while providing power to the system load.

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