Fairchild Semiconductor’s LED Backlight Boost Switches Reduce Power Losses, Minimize Sub-Harmonic Oscillation in High-Power LED Applications

Designers of high-power LEDs are challenged with preventing power losses and sub-harmonic oscillations associated with inefficient discontinuous conduction mode (DCM) boost converters. Fairchild Semiconductor's FAN7340 and FAN73402 single-channel boost controllers with integrated high-voltage dimming MOSFETs address these challenges by helping designers achieve greater efficiency, performance and better reliability in high-power lighting applications such as LED backlighting for 3D televisions and monitors.

These backlight driving boost switches use a current-mode control topology with programmable slope compensation to prevent sub-harmonic oscillation. Designed with an internal dimming and analog pulse-width modulation (PWM), these devices overcome the short falls of a DCM boost converter by achieving a fast PWM dimming response.

Both devices offer integrated protection features such as under-voltage lockout, open LED protection, and over-voltage protection that help to minimize component count. Additionally, these devices provide error prevention by generating a FAULT signal with delay if an abnormal LED string condition occurs.

Features and Benefits

* FAN7340: RDS(ON) = 3.4O at VGS = 10V, BVDSS = 400V

* FAN73402: RDS(ON) = 1.0O at VGS = 10V, BVDSS = 200V

* Wide-supply voltage range: 10V to 35V

* Cycle-by-cycle current limiting

* Internal soft-start prevents in-rush current flowing into output capacitor at startup

* Programmable switching frequency

Samples are available upon request - Delivery 8-12 weeks ARO. Both available in a 16-lead SOIC package the FAN7340 is priced at $0.85 and the FAN73402 is priced at $1.06