Analog Devices ADM1278 Hot Swap Controller with PMBus Interface allows a circuit board to be removed from or inserted into a live backplane. ADM1278 also features current, voltage, and power readback via an integrated 12-bit analog-to-digital converter (ADC), accessed using a PMBus™ interface. The load current is measured using an internal current sense amplifier that measures the voltage across a sense resistor in the power path via the HS+ and HS− pins. A default current limit of 20mV is set, but this limit can be adjusted, if required, using a resistor divider network from the internal reference voltage to the ISET pin. The ADM1278 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. The sense voltage, and therefore the load current, is maintained below the preset maximum. The ADM1278 protects the external FET by limiting the time that the FET remains on while the current is at its maximum value. This current-limit time is set by the choice of capacitor connected to the TIMER pin. In addition, a constant power foldback scheme is used to control the power dissipation in the MOSFET during power-up and fault conditions. The level of this power, along with the TIMER regulation time, can be set to ensure that the MOSFET remains within the safe operating area (SOA) limits. A programmable start-up current limit is also available for dv/dt power-up. In case of a short-circuit event, a fast internal overcurrent detector responds within 320ns and signals the gate to shut down. A 1500mA pull-down device ensures a fast FET response. The 12-bit ADC can measure the current in the sense resistor, the supply voltage on the HS+ pin, the output voltage, and the temperature at the external NPN device. A PMBus interface allows a controller to read data from the ADC. As many as 16 unique I²C addresses can be selected, depending on how the two ADRx pins are connected. Available in a 32-lead LFCSP with a RETRY pin that designers can configure for automatic retry or latch-off when an overcurrent fault occurs, the ADM1278 Hot Swap Controller is ideal for servers, power monitoring & control/power budgeting, central office equipment, and telecommunication & data communication equipment.