FAN7340: LED Backlight Driving Boost Switch

The FAN7340 is a single-channel boost controller that integrates an N-channel power MOSFET for PWM dimming using Fairchild’s proprietary planar Double-diffused MOS (DMOS) technology.

The IC operates as a constant-current source for driving high-current LEDs.

It uses Current Mode control with programmable slope compensation to prevent subharmonic oscillation. The IC provides protections including: open-LED protection, over-voltage protection, and direct-short protection for high system reliability.

The IC internally generates a FAULT signal with delay if an abnormal LED string condition occurs. PWM dimming and analog dimming functions can be implemented independently. Internal soft-start prevents inrush current flowing into output capacitor at startup.

Features

• Single-Channel Boost LED Switch
• Internal Power MOSFET for PWM Dimming: R_DS(on) = 3.4Ω at V_GS=10V, BV_DSS=400V
• Current Mode PWM Control
• Internal Programmable Slope Compensation
• Wide Supply Voltage Range: 10V to 35V
• LED Current Regulation: ±1%
• Programmable Switching Frequency
• Analog and PWM Dimming
• Wide Dimming Ratio: On Time=10µs to DC
• Cycle-by-Cycle Current Limiting
• Thermal Shutdown: 150°C
• Open-LED Protection (OLP)
• Over-Voltage Protection (OVP)
• Over-Current Protection (OCP)
• Error Flag Generation (for External Load Switch)
• Internal Soft-Start
• 15-Lead SOIC Package

Application Notes