UCC3915

The UCC3915 programmable hot swap power manager provides complete power-management, hot-swap capability, and circuit breaker functions. The only external component required to operate the device, other than power supply bypassing, is the fault-timing capacitor, C_T. All control and housekeeping functions are integrated, and externally programmable. These include the fault current level, maximum output sourcing current, maximum fault time, and startup delay. In the event of a constant fault, the internal fixed 2% duty cycle ratio limits average output power.

The internal 4-bit DAC allows programming of the fault-level current from 0 A to 3 A with 0.25-A resolution. The IMAX control pin sets the maximum-sourcing current to 1 A above the trip level or to a full 4 A of output current for fast output capacitor charging.

When the output current is below the fault level, the output MOSFET is switched on with a nominal ON resistance of 0.15 . When the output current exceeds the fault level, but is less than the maximum-sourcing level, the output remains switched on, but the fault timer starts, charging CT. Once CT charges to a preset threshold, the switch is turned off, and remains off for 50 times the programmed fault time. When the output current reaches the maximum sourcing level, the MOSFET transitions from a switch to a constant current source.

The UCC3915 can be put into sleep mode, drawing only 100 uA of supply current. Other features include an open-drain fault-output indicator, thermal shutdown, undervoltage lockout, 7-V to 15-V operation, and low-thermal resistance SOIC and TSSOP power packages.