Texas Instruments offers the UCC3912 series of hot-swap power managers

     The UCC3912 series hot-swap power manager provides complete power management, hot-swap, and circuit breaker functions. Apart from the supply bypass, the only component required to operate the device is the fault timing capacitor CT. All control and management functions are integrated and externally programmable.

     These parameters include fault current level, maximum output source current, maximum fault time, and startup delay. In the case of continuous failure, the internal fixed duty cycle of 3% limits the average output power. Internal 4-bit Dacs allow fault level current programming from 0 A to 3 A at 0.25-A resolution.

     The IMAX control pin sets the maximum source current to 1 A above fault level, when the drive is low, and to the full 4 A when the drive is high for applications that require fast output capacitor charging. When the output current is lower than the fault level, the output MOSFET is switched on with a nominal on-resistance of 0.15Ω. When the output current exceeds the fault level but is less than the maximum source level, the output remains on, but the fault timer starts to charge the CT. Once the CT is charged to a preset threshold, the switch is off and remains off for 30 times the set failure time. When the output current reaches the maximum source level, the MOSFET switches from a switch to a constant current source.

     The UCC3912 series is designed for unidirectional current flow and simulates an ideal diode in series with a power switch. This feature is particularly attractive in many applications where devices power a common bus, such as SCSI Termpwr. And all series can be put into sleep mode, requiring only 1-µA of power current. The SHTDWN pin has a preset threshold hysteresis that allows the user to set a time delay at startup for power sorting. Other features include leak-open FAULT output indicator, thermal shutdown, voltage locking and low thermal resistance small profile package.