48V Hot Swap Controller with Sequencer

The LTC4253A-ADJ negative voltage Hot Swap™ controller allows a board to be safely inserted and removed from a live backplane. Output current is controlled by three stages of current-limiting: a timed circuit breaker, active current limiting and a fast feedforward path that limits peak current under worst-case catastrophic fault conditions. The LTC4253A-ADJ latches off after a circuit fault.

Undervoltage and overvoltage detectors with adjustable thresholds and hystereses disconnect the load whenever the input supply exceeds the desired operating range. The LTC4253A-ADJ's supply input is shunt-regulated, allowing safe operation with very high supply voltages. A multifunction timer delays initial start-up and controls the circuit breaker's response time. The circuit breaker's response time can be accelerated by sensing excessive MOSFET drain voltage. An adjustable soft-start circuit controls MOSFET inrush current at start-up.

Three power good outputs can be sequenced to enable external power modules at start-up or disable them if the circuit breaker trips. The LTC4253A-ADJ is available in 20-pin SSOP and 20-pin (4mm × 4mm) QFN packages.

Notes

LTC4253

LTC4253A

Recommend LTC4253B for new designs

LTC4253A-ADJ

Recommend LTC4253B for new designs

LTC4253B

Applications

* -48V Distributed Power Systems

* Negative Power Supply Control

* Central Office Switching

* High Availability Servers

* Disk Arrays

* Obsolete - Contact Analog Devices for Potential Replacement

* Allows Safe Board Insertion and Removal from a Live – 48V Backplane

* Floating Topology Permits Very High Voltage Operation

* Adjustable Analog Current Limit with Breaker Timer

* Fast Response Time Limits Peak Fault Current

* Adjustable Undervoltage/Overvoltage Protection with ±1% Threshold Accuracy