The ADM1276-3ACPZ-RL from Analog Devices is a Hot Swap Controller IC that has been designed to allow a circuit board to be removed from or inserted into a live backplane. It requires an input voltage of 2.95 - 20 V. This eFuse IC consists of 12-bit ADC, control logic and integrated PMBus interface, timer, reference select, gate drive/logic, charge pump, amplifier, LDO regulator, and protection circuitries. It uses an internal current-sense amplifier to measure the load current in the power path via the SENSE+ and SENSE- pins. It limits the current through the sense resistor by controlling the gate voltage of an external N-Channel FET in the power path, via the GATE pin, thereby maintaining both the sense voltage and load current below the preset maximum. This controller uses an optimal capacitor connected to the TIMER pin to limit the time that the FET remains ON while the current is at its maximum value, ensuring the protection of the FET device. It also supports a fold-back resistor network to actively lower the current limit as the voltage across the FET is increased.

The hot swap controller includes a fast internal over-current detector that responds within 370 ns and signals the gate to shut down during short-circuit events. It also integrates over-voltage and under-voltage protection to the OV and UV pins. This controller IC uses a built-in 12-bit ADC to measure the current in the sense resistor as well as the supply voltage on the SENSE+ pin. It allows an external controller to read current and voltage values from the ADC using a PMBus interface based on pre-determined PMBus commands. This eFuse IC’s integrated LATCH pin can be configured for automatic retry or latch-off when an over-current fault occurs. It is available in a surface-mount package that measures 5 x 5 mm and is ideal for power monitoring and control/power budgeting, central office equipment, telecommunications, data communication equipment, PC, and server applications.