FAN5776: Synchronous Boost and Series / Parallel 10-LED Driver

The FAN5776 is a synchronous, constant-current LED driver capable of efficiently driving up to ten LEDs in a five-string, two-series LEDs per string configuration. Optimized for small form-factor applications, the 1.8 MHz switching frequency allows the use of tiny chip inductors and capacitors.

For safety, the device features integrated over-voltage, short-circuit, and thermal shutdown protections. In addition, input under-voltage lockout protection is triggered if the battery voltage is too low.

The FAN5776 is comprised of low-dropout, high-side current sources, enabling a high efficiency delivery of power from the battery to the LEDs. The LED current control is established with a series RSET resistor, which is connected between the internal voltage reference on the chip and ground.

During operation, FAN5776 holds the boost regulator’s voltage on COUT during the off cycle of the PWM dimming, which helps minimize audible noise.

The FAN5776 is available in a very low profile, small-form-factors 1.42 x 1.66 x 0.50 mm, 12-bump WLCSP package that is “green” and RoHS compliant.

Features

• Synchronous Current-Mode Boost Converter
• Drives up to 10 LEDs at 25 mA Each in a Configuration of 5 Strings of 2 LEDs in Series
• 5 LED Outputs: High-Side Current Sources
• Two Default Groups of 3x2-LED Channels and 2x2-LED Channels with Individual Enable and PWM Dimming Control to Support Various Lighting Applications, such as:
  • Backlighting of Dual-LCD Displays, LCD Display Plus Keypad Illumination
• Backlighting of Dual-LCD Displays, LCD Display Plus Keypad Illumination
• Boost PFM Mode Maximizes Efficiency Under Light Loads
• 2.3 V to 5.5 V Input Voltage Range
• 1.8 MHz Switching Frequency
• Input Under-Voltage Lockout (UVLO)
• Output Over-Voltage Protection (OVP)
• Short-Circuit and Thermal Shutdown (TSD) Protection
• 12-Bump, 0.4 mm Pitch, 1.42 x 1.66 x 0.50 mm WLCSP