Hot Swap Controller provides open circuit detection.

Press Release Summary:

Able to handle positive voltages from 10.8-80 V, LT4256 IC allows boards to be inserted into live backplanes without risking damage to connectors or causing glitches in supplies. Unit has adjustable analog foldback current limit and is available in 3 versions with latch off, automatic restart, or both. Model LT4256-3 also provides open circuit detect output. Features include under- and over-voltage detection and power good outputs.

Original Press Release:

Positive 80 Volt Hot Swap Controllers Provide Open Circuit Detection

MILPITAS, CA - April 21, 2004 - Linear Technology Corporation introduces the LT4256, a high voltage Hot Swap(TM) controller that handles positive voltages from 10.8V up to 80V, making it ideal for the wide supply ranges in telecom applications. The IC allows boards to be inserted into live backplanes without risking damage to the connectors or causing glitches in the supplies. The LT4256 has an adjustable analog foldback current limit. If the supply remains in current limit for more than an adjustable time, the N-channel MOSFET shuts off and the Power Good output asserts low.

The LTC4256 is available in three versions. After a fault, the LT4256-1 latches off until the UV pin is cycled low, the LT4256-2 automatically restarts after a timeout delay, whereas the LT4256-3 can be set to either latch off or automatically restart. The LT4256-3 also provides an open circuit detect output to indicate abnormally low load current conditions or no load presence at all. In addition, the parts feature strong Gate pull up currents to accommodate higher leakage MOSFETs or parallel devices.

The Power Good output can also be used to enable a DC/DC converter module, providing power to the board once the voltages and currents exceed the selected levels. Undervoltage and overvoltage levels are chosen by an external resistor string from Vcc and allow the user to set limits on when the board turns on and off.

The LT4256-1 and LT4256-2 are offered in an 8-pin SO package, and the LT4256-3 is in a 16-lead SSOP package. The ICs are available in commercial and industrial temperature ranges. Pricing starts from $1.75 each for 1,000-piece quantities.

Summary of Features: LT4256

Allows Safe Board Insertion & Removal From A Live, High-Voltage Backplane

Controls Supply Voltages from 10.8V to 80V

Foldback Current Limiting

Undervoltage & Overvoltage Detection

Power Good Outputs

Open Circuit Detect (LT4256-3)

Latch Off (LT4256-1) or Automatic Retry (LT4256-2)

8-Pin SO (LT4256-1/LT4256-2) & 16-Lead SSOP (LT4256-3)

Company Background

Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include operational, instrumentation and audio amplifiers; voltage regulators,power management devices, DC-DC converters and voltage references; comparators; monolithic filters; communications interface circuits; one-chip data acquisition sub-systems; pulse-width modulators and sample-and-hold devices; and high frequencydevices. Applications for Linear Technology's high performance circuits include wireless and broadband telecommunications infrastructure, cellular telephones, networking products and satellite systems, notebook and desk top computers, computer peripherals, video/multimedia, industrial and medical instrumentation, automotive electronics, factory automation, process control, military and space systems, and high-end consumer products including digital cameras, MP3 players and other electronic products.

Note: LT, AND LTC are registered trademarks of Linear Technology Corp.

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