AN-9765 - LED Backlight Driving Boost Switch
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چکیده
FAN7340 is a single-channel boost controller that integrates an N-channel dimming MOSFET using Fairchild’s proprietary planar DMOS technology. The IC operates as a constant-current source for driving high-current LEDs. FAN7340 uses a current-mode control with programmable slope compensation to prevent sub-harmonic oscillation and provides protections such as Open-LED Protection (OLP) and Over-Voltage Protection (OVP) for system reliability. The IC internally generates a FAULT_OUT signal with a delay in case of abnormal LED string conditions. A dimming function is implemented with a PWM or analog method. An internal soft-start function prohibits inrush current flowing into the output capacitor during startup. The circuit operation and design procedure are explained in the following sections.
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