USB Power Manager & Li-Ion Battery Charger Delivers 700mA to System Load

For automotive, Firewire, or other high-voltage applications, the LTC4098 provides Bat-Track™ control of a Linear Technology companion switching regulator up to 38V operating input (60V transient), maximizing battery charger efficiency, minimizing heat dissipation, and providing for a seamless transition between USB and higher voltage power sources.

The LTC4098 provides an over-voltage protection (OVP) circuit up to 66V on the USB input – requiring only an external NFET/resistor combination – preventing damage caused by accidental application of high voltage. The LTC4098’s instant-ON operation ensures system load power at plug-in even with a dead battery. Its onboard ideal diode guarantees that ample power is always available to VOUT even if there is insufficient power at the LTC4098’s two input pins. The IC’s ideal diode controller can be used to drive the gate of an optional PFET, reducing the impedance to the battery to 30mOhm or less.

The LTC4098's full-featured single-cell Li-Ion/Polymer battery charger allows the load current to exceed the current drawn from the USB port while conforming to USB load specifications. For fast charging, the IC's switching input stage converts nearly all of the 2.5W available from the USB port to system current, enabling up to 700mA from a 500mA limited USB port. There is also 1.5A charge current available when wall powered. Further, the charger includes thermal limiting, automatic recharge, stand-alone operation with automatic charge termination and fixed duration safety timer, low voltage trickle charging, bad battery cell detection and a thermistor input for temperature-qualified charging. An additional feature of the IC is a suspend LDO that prevents battery drain when a device is connected to a suspended USB port.