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  • Single Channel Positive High Voltage Hot Swap Controller

  • Created: Jan 08, 2017

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Hot swapping is a term used in replacing a component with the power still connected. Equipment and system that have vital and critical role requires being continuously operational with no down time. With hot swapping, it removes the need to power down equipment when replacing components. Even hot swapping; when circuit boards are inserted into system carrying live supply voltage, high inrush currents often result due to the charging of bulk capacitance that resides across the circuit board’s supply pins. These current spikes can cause the system’s supply voltage to temporarily go out of regulation causing data loss or system lock-up and can permanently damage to on board components. The MIC2587R is designed to address these issues by limiting the maximum current that is allowed to flow during hot swap event. It implements a constant-current control loop at turn-ON and incorporate input voltage supervisory function and overcurrent protection.

The design is a single channel hot swap controller that uses the MIC2587R. It uses an external, current sense resistor in series with the drain of the external MOSFET to measure the current flowing into the load. It is also equipped with an electronic circuit breaker that protects other system components against large-scale current output. The current sense resistor (RSENSE) is connected to the VCC (+) and SENSE (-) of the hot swap controller. The current limit threshold is set via the RSENSE. The CTIMER is used to determine the length of the time delay for which the controller remains in current limit before the circuit breaker is tripped. The hot swap controller pin power-good output signal (PWRGD) is connected to the ON/nOFF pin of the DC-DC converter module. It is used to enable the DC/DC converter module. The PWRGD will be high impedance when the FB pin voltage is higher than the Voltage threshold and will pull-down to GND when the VFBH pin voltage is lower than the VFBL voltage threshold. The ON pin of the hot swap controller is used to enable the controller to commence a start-up sequence upon card insertion or to disable controller operation upon card removal.

The hot swap design is applicable in live equipment; it makes swapping of component without interruption to the equipment or system. In industries like telecom and medical, a no down time system of swapping components during maintenance and upgrading is important. The design can operate at +12V/+24V/+48V distributed power system.z



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