Dual-Port Powered USB Controller The ISL6436 is a USB dual-port power supply controller, fully independent over-current (OC) fault protection IC. Operating in the +2.5 V to +5.5 V range, this device features internal current monitoring, accurate current limit, integrated power switch and protection by a current limit delay latch system. The ISL6436's current sense and limit circuitry sets the rated current limit to 1A, making this device ideal for applications in USB port power management. The ISL6436 OC provides fault notification, precise current limiting and a consistent timed latch which isolates and protects the voltage bus in the presence of OC events or short circuits. The 12 ms time to latch the switch is adjacent to the independent electrical or thermal condition and the OC response time is negatively related to the OC size. Each ISL6436 integrates an 8-pin SOIC second package of 80mΩ N-channel MOSFET power switches for power control. The output of each switch is provided by a constant current source with a controlled ramp register voltage. This provides a soft-start turn-on to eliminate the inrush current caused by the bus voltage sag while charging the load capacitance. Makes the input and independent per-channel fault reporting output compatible with 3V and 5V logic, allowing external control and monitoring. The undervoltage lockout feature of the ISL6436 prevents turning on properly unless the state and VIN > 2.5V of the output are present. The ISL6436 is initially turned on to prevent fault reporting from blanking the fault signal. The rising and falling edge output current limits the voltage rise so that both the inrush current and the rate of change of the voltage are limited and independent of the load. This will reduce surges due to supply droop and eliminate the need for external EMI filters. During operation, once the OC condition is detected, the corresponding output current is limited to 12 msec and is allowed to pass under transient conditions. If there is still current limit after the current limit period has elapsed, then the output latches off and the corresponding pull-fault is reported low. The fault signal is latched until the reset low enable signal is pulled high, at which point the fault signal will clear.