The I2C port also allows the user to read back system status information. The LTC4099’s switching PowerPath™ topology seamlessly manages power flow between a wall adapter or USB port and the device’s battery while preferentially providing power to the system load.
With companion chip input voltages ranging up to 38V (60V transients), the LTC4099 provides a seamless transition between USB and higher voltage power sources.
The LTC4099 prevents damage caused by accidental application of high voltage on the USB input with an overvoltage protection (OVP) circuit – protection up to 68V requires only an external NFET/resistor combination. The LTC4099’s "instant-ON" operation ensures system load power at plug-in even with a dead battery.
The LTC4099’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 current, enabling up to 600mA charge current or 700mA system load current from a 500mA limited USB port. There is also 1.5A charge current available when wall powered.
| Summary of Features: LTC4099 | |
 | Switching Regulator with Bat-Track Adaptive Output Control Makes Optimal Use of Limited Power Available from USB Port to Charge Battery and Power Application |
| I2C Port for Optimal System Performance and Status Information |
| Input Overvoltage Protection (up to 68V) |
| Bat-Track Control of External Step-Down Switching Regulator Maximizes Efficiency from Automotive and Other High Voltage Sources |
| Instant-On Operation with Low Battery |
| Ideal Diode Seamlessly Connects Battery when Input Power is Limited |
| Overtemperature Battery Conditioner |
| Full Featured Li-Ion/Polymer Battery Charger |
| 1.5A Maximum Charge Current with Thermal Limiting from Wall Adapter |
| 700mA Maximum Current Available to System Load from a 500mA USB Port |
| Slew Control Reduces Switching EMI |
| Ultra-Thin (0.55mm) 20-Lead 3mm × 4mm QFN Package Links & Datasheet |
