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Hot Swap controller drives ATCA mezzanine cards

Posted: 03 Sep 2007 ?? ?Print Version ?Bookmark and Share

Keywords:Hot Swap controller? ATCA mezzanine cards? network platforms?

Linear Technology Corp. has introduced the LTC4223, a 12V and 3.3V dual supply Hot Swap controller that enables live insertion and removal of mezzanine cards used on AdvancedTCA carrier blades, MicroTCA systems or proprietary network platforms.

The PICMG has developed the Advanced Mezzanine Card (AMC) standard that defines the requirements for add-on modules to expand the functionality of an AdvancedTCA carrier board, an open-industry standard intended to address the rapidly changing needs of communications network infrastructure. These modules are also suitable for MicroTCA applications, an emerging standard that provides a scaled version of ATCA for more compact and price-sensitive applications. The LTC4223 is the first Hot Swap controller targeted specifically for AMC/MicroTCA applications that meets the full requirements outlined in the PICMG AMC standard.

LTC4223 provides independently controlled turn-on and shutdown of the 12V main and 3.3V auxiliary supply rails used on the mezzanine card. The main 12V rail is controlled via an external N-channel MOSFET, while the 3.3V rail uses an integrated 0.3 switch for auxiliary or management power up to 165mA. For the 12V rail, key features include a fast acting current limit in the event of short circuit faults, with guaranteed 5 percent accuracy. An external current sense resistor adjusts the current trip threshold.

LTC4223 also provides a 12V current sense monitoring output that can be connected to a low cost ADC like the LTC2450. Separate power good outputs are available with 3 percent accurate thresholds set 10 percent and 15 percent below the 12V and 3.3V rails, respectively. A fault output alerts the host processor if an overcurrent fault has occurred on either supply, while a separate VCC pin decouples the IC supply from faults on the 3.3V rail.

The chip includes a gate-source clamp to protect the external MOSFET from hard shorts on the output. Absolute maximum ratings of 20V and 10V for the respective supplies ensure ruggedness when confronted with short overvoltage spikes and ringing present in harsh Hot Swap environments.

LTC4223 is offered in two versions: the LTC4223-1 latches off after a fault while the LTC4223-2 provides automatic retry after a fault. Specified over the commercial and industrial temperature ranges, the LTC4223 is offered in 16-lead SSOP and 5mm x 4mm DFN packages.

Available today, the device sells at $2.10 each in 1,000-piece quantities.

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