NCP1422LEDGEVB: High Current LED Driver Evaluation Board

The NCP1422 is a monolithic, micropower, high frequency, step-up switching converter IC designed for battery-powered handheld electronics with load currents up to 800 mA. It integrates a synchronous rectifier (Sync-Rect) to improve efficiency and eliminate external Schottky diodes. The high switching frequency of the NCP1422 (up to 1.2 MHz) allows the use of thin, small-size inductors and output capacitors. When the device is disabled, the internal conduction path from the battery to the load is completely blocked, isolating the load from the battery. This True-Cutoff feature reduces the shutdown current to typically only 50 nA. A Ring-Killer is also integrated to eliminate high-frequency ringing in discontinuous conduction mode. Finally, low battery detector, logic-controlled shutdown, cycle-by-cycle current limit, and thermal shutdown provide value-added features for a variety of battery-powered applications. With all these features turned on, the quiescent supply current is typically only 8.5 uA. The device is available in a compact, low-profile DFN-10 package. The NCP1422LED Evaluation Board uses the NCP1422 to drive high power white LEDs. The low voltage MOSFET switching circuit on the board can pulse low and high LED currents, as in focus and flash applications. The circuit is configured to minimize the power dissipated in the current sense resistor and the effect of lot-to-lot variations in LED forward voltage (VF) on the LED current. Application note AND8171/D describes how to design this circuit.


The NCP1422 is a monolithic, micro-power, high-frequency, step-up switching converter IC designed for battery operated hand-held electronic products with up to 800 mA loading. It integrates a synchronous rectifier (Sync-Rect) to improve efficiency and to eliminate the external Schottky Diode. The NCP1422's high switching frequency (up to 1.2 MHz) allows for a low profile, small sized inductor and output capacitor to be used. When the device is disabled, the internal conduction path from the battery to the load is fully blocked, which isolates the load from the battery. This True-Cutoff function reduces the shutdown current to typically only 50 nA. A Ring-Killer is also integrated to eliminate high-frequency ringing in discontinuous conduction mode. Finally, a Low-Battery Detector, Logic-Controlled Shutdown, Cycle-by Cycle Current Limiting and Thermal Shutdown provide value-added features for various battery operated applications. With all these functions on, the quiescent supply current is typically only 8.5 uA. This device is available in the compact and low profile DFN-10 package. The NCP1422LED evaluation board uses the NCP1422 to drive a high power, white LED. A low voltage MOSFET switch circuit on the board can be pulsed to switch between a low and high LED current as would be found in a focus and flash application. The circuit is configured to minimize power dissipation in the current sense resistor and the effects of lot-to-lot LED forward voltage (VF) variation on LED current. Application note AND8171/D describes how to design this circuit.