48V Hot-Swap Controllers with External R

The MAX5949A/MAX5949B are hot-swap controllers that allow a circuit card to be safely hot plugged into a live backplane. The MAX5949A/MAX5949B operate from -20V to -80V and are well-suited for -48V power systems. These devices are pin and function compatible with the LT4250 and pin compatible with the LT1640.

The MAX5949A/MAX5949B provide a controlled turn-on to circuit cards preventing glitches on the power-supply rail and damage to board connectors and components. The MAX5949A/MAX5949B provide undervoltage, overvoltage, and overcurrent protection. These devices ensure the input voltage is stable and within tolerance before applying power to the load.

Both the MAX5949A and MAX5949B protect a system against overcurrent and short-circuit conditions by turning off the external MOSFET in the event of a fault condition. The MAX5949A/MAX5949B also provide protection against input voltage steps. During an input voltage step, the MAX5949A/MAX5949B limit the current drawn by the load to a safe level without turning off power to the load.

Both devices feature an open-drain power-good status output (PWRGD-bar for the MAX5949A or PWRGD for the MAX5949B) that can be used to enable downstream converters.

The MAX5949A/MAX5949B are available in an 8-pin SO package. Both devices are specified for the extended -40°C to +85°C temperature range.

Applications

* -48V Distributed Power Systems * Base-Station Line Cards * Central-Office Line Cards * Central-Office Switching * Negative Power-Supply Controls * Network Routers and Switches * Server Line Cards * Telecom Line Cards

* Allow Safe Board Insertion and Removal from a Live -48V Backplane

* Pin and Function Compatible with LT4250L (MAX5949A)

* Pin Compatible with LT1640L (MAX5949A)

* Pin and Function Compatible with LT4250H (MAX5949B)

* Pin Compatible with LT1640H (MAX5949B)

* Circuit-Breaker Immunity to Input Voltage Steps and Current Spikes

* Withstand -100V Input Transients with No External Components

* Programmable Inrush and Short-Circuit Current Limits

* Operate from -20V to -80V

* Programmable Overvoltage Protection

* Programmable Undervoltage Lockout

* Power Up into a Shorted Load

* Power-Good Control Output