Catalog
LED Driver, 8-Channel, Programmable
Key Features
• Programmable, Individual Output PWM Control with 6-Bit Counter
• Eight 30 mA Universal Current Sources with 5-Bit Programmable Logarithmic Brightness Control
• Read/Write Serial Interface for Convenient Programming
• Patented (1X, 1.33X, 1.5X and 2X) Charge Pump for Higher Forward Voltage LEDs (e.g. 4.1 V)
• Soft-Start Power-On-Reset (POR)
Description
AI
The NCP1840 is a highly integrated general purpose LED driver with the ability to drive up to eight LEDs. A high efficiency, low noise, charge pump allows the use of higher forward voltage LEDs while automatically maintaining a low operating battery voltage. Each of the eight driver currents is fully programmable, each utilizing a 5-bit current DAC. The current can be turned on or off achieving various dimming levels using a programmable 6-bit counter. The full-scale current of all eight current DACs is set by an external resistor. The NCP1840 requires only five small ceramic capacitors and one resistor to form a complete LED power supply and current controller. By utilizing a fourth mode (1.33x), the NCP1840's charge pump optimizes efficiency based on the voltage across the LED current sources. 1.33x mode can offer approximately 10 percent more efficiency than a typical 1.5x mode. The device powers up in 1x mode and will automatically boost to higher modes whenever any enabled LED current source begins to enter dropout. The first dropout switches the device into 1.33x mode, and subsequent dropouts switch the NCP1840 into 1.5x and 2x modes, respectively.
