LM5069 datasheet(9/22 Pages) NSC

9 / 22 page

Block Diagram

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Functional Description

The LM5069 is designed to control the in-rush current to the

load upon insertion of a circuit card into a live backplane or

other "hot" power source, thereby limiting the voltage sag on

the backplane’s supply voltage, and the dV/dt of the voltage

applied to the load. Effects on other circuits in the system are

minimized, preventing possible unintended resets. A con-

trolled shutdown when the circuit card is removed can also

be implemented using the LM5069. In addition to a program-

mable current limit, the LM5069 monitors and limits the

maximum power dissipation in the series pass device to

maintain operation within the device Safe Operating Area

(SOA). Either current limiting or power limiting for an ex-

tended period of time results in the shutdown of the series

pass device. In this event, the LM5069-1 latches off until the

circuit is re-enabled by external control, while the LM5069-2

automatically restarts with defined timing. The circuit breaker

function quickly switches off the series pass device upon

detection of a severe over-current condition. The Power

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FIGURE 1. Basic Application Circuit

LM5069 Datasheet(PDF) 9 Page - National Semiconductor (TI)