Efficient Methods for Driving High Brightness LEDs

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The LED lighting market is experiencing tremendous growth and with this growth comes the need to drive LEDs in a cost effective and efficient manner. Fairchild Semiconductor offers solutions that are highly efficient and offer significant cost benefits.

Fairchild’s Solutions

The FAN7554 is a fixed frequency current mode PWM controller. It is specially designed for off-line and DC to DC converter applications with minimal external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, an ON/OFF control, a high gain error amplifier, a current sensing comparator and a high current totem-pole output. The FAN7554 has various protection functions such as over load protection, over current protection, and over voltage protection, including built-in auto restart circuit.

A constant current supply (LED driver), is designed in the same manner as a conventional switch mode power supply with the exception that output current is controlled rather than output voltage. The output voltage needs to be designed based on the number of LEDs that are in series. The feedback loop monitors the output current to produce a constant current to drive the LEDs.

 

FEATURES Current Mode control Pulse-by-pulse current limiting Low external components Under Voltage Lockout (UVLO): 9V/15V Operating current: Typ. 7mA On/Off control Over Load Protection (OLP) Over Voltage Protection (OVP) Over Current Protection (OCP) Over Current Limit (OCL) Operating frequency up to 500kHz 1A totem-pole output current

APPLICATIONS Off-line and DC-to-DC converters

 

 

 

 

 

 

The FSQ0370RNA, a green FPSTM e-SeriesTM power switch, consists of an integrated current mode Pulse Width Modulator (PWM) and avalanche rugged 700V SenseFET. It serves as the power supply controller and primary side switch. This green FPS e-Series family of controllers integrates a controller and MOSFET into a single device saving space and simplifies the overall design.

 

FEATURES High efficiency as it consumes only 0.8W at 230VAC and 0.5W with burst mode operation Low operating current (3mA) Built-in protection features (OVP, OLP, TSD) Internal start-up circuit and built-in soft start

APPLICATIONS Auxiliary power supply for PCs and servers SMPS for VCR, SVR, STB, DVD and DVCD players, printers, fax machines and scanners Adapter for camcorders Off-line and DC-to-DC converters

 

 

 

 Featured Products

Part Number		Description	Data Sheet	App. Notes
FAN7554D		Intelligent Current Mode PWM Control IC
FAN7554DTF		Intelligent Current Mode PWM Control IC
FEB157		Off-line High Brightness LED Driver Evaluation Board Kit
FSQ0370RNA		SMPS Green Power Switch, 3A, 700V

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