ISL6111
Current Regulated PCI Hot Plug Power Switch Controller

Key Features

• Active Current Regulation for Protection
• Adjustable Current Regulation Duration and Magnitude
• Internal MOSFET Switches for +12V and -12V Outputs
• Provides Fault Isolation
• Adjustable Turn-On Slew Rate
• Minimum Parts Count Solution
• No Charge Pump
• 1µs Response Time to Over Current
• Pb-Free leadframe

Description

The ISL6111 is designed for use in PCI and PCI-X applications where active current regulation protection of the motherboard from an abnormal PCI load card is desired.

With the addition of two discrete power MOSFETs and a few passive components, the ISL6111 provides power control for the four legacy supplies (-12V, +12V, +5V, +3.3V) to a PCI or PCI-X slot. This IC integrates the +12V and -12V current sensing and regulation switches. On the 25W capable 3.3V and 5V rails, current regulation (CR) protection is provided by sensing the voltage across external current-sense resistors and modulation of the gate voltage bias on the external N-channel power MOSFETs.

During initial power-up of the +12V bias supply, the ENABLE (EN), Power Good (PG), fault monitoring and reporting function functions are inhibited if bias voltage <10V. Once the FETs are enabled they are soft started into the load thus eliminating supply rail disturbances.

Upon a failure that quickly causes a load current greater than the programmed CR level on any voltage supply, the ISL6111 enters its current regulation (CR) mode, limiting the load current to the user programmed level for the user determined period of time. The CR level and duration are set by a single resistor and capacitor respectively. At the end of the CR duration all the switches will latch off pulling the outputs low along with the CRTIM (current regulation timer) and FLTN (fault not) pins indicating a latch-off due to an over current (OC) condition. If a severe OC condition should occur, then the ISL6111 immediately latches off all outputs and sets the FLTN output low.

During operation, if any of the positive voltages falls below the minimum PCI specified levels the power good (PG) output will pull low indicating a non compliant voltage to a load. PG is an open drain output as is FLTN.

The CRSET pin allows programming of the current regulation levels to be scaled up or down from the PCI specified levels via a resistor connected between the CRSET pin and ground.

All faults and latches are cleared by ENABLE being deasserted low.

Applications

• PCI
• PCI-X 1.0