FAN5340: Synchronous Constant-Current. Series Boost LED Driver with FAN5340: Synchronous Constant-Current Series Boost LED Driver with Integrated Load Disconnect Product Presentation

Overview There has been a proliferation of small TFT LCD displays being used in portable electronics today These LCDs require white LEDs to backlight it in order to display that images on it White LEDs can be driven in series of parallel LED drivers must not only provide excellent efficiency performance to prolong operation of the portable device but also provide a good visual experience Small form factor for the LED driver and the solution itself are also important factors since space is at a premium

Introduction FAN5340 is a synchronous constant-current series boost LED driver with load disconnect that drives 2 to 4 white LEDs Compact and cost effective solution that provides superior performance Up to 85% efficiency Excellent LED Current Linearity Integrated Load Disconnect Small form factor: WLCSP-8, 1.57mm x 1.57mm Driving the LEDs in series provides one excellent benefit – it ensures that all LEDs will have equal brightness

FAN5340 Synchronous Constant-Current Series Boost LED Driver Reduces Start-up Transients and Audible Interference Features Synchronous Operation Up to 85% Efficiency 500mW Output Power Drives 2 to 4 WLEDs @ 40mA Integrated Disconnect Load Lower Audible Noise Saves Power during PWM Dimming Excellent PWM Linearity 1.2MHz Switching Frequency Output Over-Voltage Protection Pkg: WLCSP-8 & 3x3mm MLP Status Mobile Handsets MP3 Players Mobile Internet Devices Rugged Handheld PCs Portable Medical Equipment

FAN5340 Efficiency 4 LEDs in Series 3 LEDs in Series

FAN5340: LED Current Linearity FAN5340 dims the LEDs through PWM dimming at 300Hz to 1kHz To achieve linear LED current especially at low brightness levels, duty cycle is <5% and requires a low PWM frequency i.e. 300Hz The graph on the left shows LED current linearity over the full range while the one on the right is for duty cycle <2%

FAN5340: Load Disconnect FAN5340 integrates true load disconnect It provides 2 benefits: Prevents leakage current to LEDs from input when FAN5340 is OFF Reduces audible noise generated by COUT capacitor Large voltage ripples on this capacitor causes audible noise by mechanical deformation in the ferroelectric compounds

FAN5340 Features & Benefits High Efficiency Up to 85% peak efficiency to minimize power consumption in portable products Serial Driver Drives LEDs in series to enable equal level of brightness for all LEDs No need for current matching between channels Load Disconnect Prevents reverse leakage current by disconnecting LEDs when FAN5340 is OFF to reduce current Reduces audible noise in COUT capacitor LED Current Linearity Linear relationship between LED current and duty cycle (full range including low duty cycle) Uniform dimming especially at low LED current Small Form Factor Saves PCB space in portable products WLCSP-8 package occupies <2.5mm2

FAN5340 + FAN5640 Keypad Lighting LCD Backlight

Pricing & Availability Fairchild Part Number Package Unit Price @ 1ku Availability FAN5340UCX WLCSP-8 $0.75 Now FAN5340MPX MLP-8 $0.79 August 2010

Technical Materials FAN5340 Datasheet http://www.fairchildsemi.com/ds/FA/FAN5340.pdf FAN5340 Product Overview http://www.fairchildsemi.com/pf/FA/FAN5340.html Evaluation Boards Request via Sales Center Samples http://www.fairchildsemi.com/ShoppingExperience/action/displayItems?itemType=SAMPLE&gpn=FAN5340

Marketing & Apps Contacts Marketing Contact Wayne Seto wayne.seto@fairchildsemi.com +1-408-822-2197 Applications Support Mark Barycza mark.barycza@fairchildsemi.com +1-408-822-2315