The LTC®3783 is a current mode LED driver and boost, flyback and SEPIC controller that drives both an N-channel power MOSFET and an N-channel load PWM switch. When using an external load switch, the PWMIN input not only drives PWMOUT, but also enables controller GATE switch ing and error amplifier operation, allowing the controller to store load current information while PWMIN is low. This feature (patent pending) provides extremely fast, true PWM load switching with no transient overvoltage or undervoltage issues; LED dimming ratios of 3000:1 can be achieved digitally, avoiding the color shift normally associated with LED current dimming. The FBP pin allows analog dimming of load current, further increasing the effective dimming ratio by 100:1 over PWM alone.
FEATURES
■ True Color PWMTM Delivers Constant Color with 3000:1 Dimming Ratio
■ Fully Integrated Load FET Driver for PWM Dimming Control of High Power LEDs
■ 100:1 Dimming from Analog Inputs
■ Wide FB Voltage Range: 0V to 1.23V
■ Constant Current or Constant Voltage Regulation
■ Low Shutdown Current: IQ = 20µA
■ 1% 1.23V Internal Voltage Reference
■ 2% RUN Pin Threshold with 100mV Hysteresis
■ Programmable Operating Frequency (20kHz to 1MHz) with One External Resistor
■ Synchronizable to an External Clock Up to 1.3fOSC
