L6740L datasheet(40/44 Pages) STMICROELECTRONICS

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LTB technology™

L6740L

40/44

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Gain Design. Through the LTBGAIN pin it is possible to modify the slope of the LTB

Ramp in order to modulate the entity of the LTB response once the LT has been

detected. In fact, the response depends on the board design and its parasitics requiring

different actions from the controller.

Leaving the LTBGAIN pin floating, the maximum pulse-width is programmed. The slope

of the LTB ramp will be equal to 1/2 of the OSC ramp slope.

Connecting RLTBGAIN to GND, the LTB Ramp slope can be modified as follow:

Where ILTBGAIN is the current sunk from LTBGAIN pin and IOSC is the OSC current

(20

µA plus the current sunk from the OSC pin).

LTB TechnologyTM Design Tips.

–

Decrease RLTB to increase the system sensitivity making the system sensitive to

smaller dVOUT.

–

Increase CLTB to increase the system sensitivity making the system sensitive to

higher dV/dt.

–

Increase RLTBGAIN to increase the width of the LTB pulse reducing the system

ring-back.

LTBRamp

Slope

OSC

Slope

LTBGAIN

OSC

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L6740L 数据表(PDF) 40 Page - STMicroelectronics