Milpitas, Calif.—Linear Technology's LTC3783, a PWM LED driver that boasts a 3000:1 dimming range for high-power LED strings and clusters, uses digitally-based True Color circuitry to eliminate the color shift normally associated with traditional LED current dimming. Additionally, the chip's FPB pin enables analog dimming, increasing the effective dimming ratio by 100:1 over that using the PWM alone.
Integrated drivers for power and load MOSFET switches and an adjustable feedback voltage (zero to 1.23 volts, accurate to 1 percent) are designed to simplify this part's use in higher-power LED lighting applications (up to 1.5 amps with external MOSFET). One resistor sets operating frequency from 20 kHz to 1 MHz. The LTC3783 can be synchronized to an external clock. Programmable soft-start limits inrush current during startup, preventing input current spikes. The chip's "No RSENSE" circuitry, for higher efficiency in low-to medium-power applications, uses the on-resistance of a MOSFET to eliminate the current-sense resistor. The chip can also be applied as a buck, boost, SEPIC, or flyback controller and as a constant-current/constant-voltage regulator in general purpose applications.
Click here to access the device's datasheet. The LTC3783, in a 16-lead 5-by-4 mm DFN as well as a TSSOP, is rated for operation from -40 to +85°C. It's priced at $2.85 each in 1k pieces.
Linear Technology, 1-800-4-LINEAR, www.linear.com