Up to 1.5 A Constant 
Current Switching
Regulator for LEDs with
ON/OFF Function
The NCP3066 is a monolithic switching regulator designed to deliver constant current for powering high brightness LEDs. The device has a very low feedback voltage of 235 mV (nominal) which is used to regulate the average current of the LED string. In addition, the NCP3066 has a wide input voltage up to 40 V to allow it to operate from a 12 Vac or a 12−36 Vdc supply, commonly used for lighting applications as well as unregulated supplies such as rechargeable batteries. The NCP3066 switching regulator can be configured in Step−Down (Buck), Step−Up (Boost) and Voltage−Inverting topologies with a minimum number of external components. The ON/OFF pin provides PWM dimming capability or a low power shutdown mode.
Features
• Integrated 1.5 A Switch
• Input Voltage Range from 3.0 V to 40 V
• Logic Level Shutdown Capability
• Low Feedback Voltage of 235 mV
• Cycle−by−Cycle Current Limit
• No Control Loop Compensation Required
• Frequency of Operation Adjustable up to 250 kHz
• Analog and Digital PWM Dimming Capability
• Internal Thermal Shutdown with Hysteresis
• NCV Prefix for Automotive and Other Applications Requiring Site and Control Changes
• These are Pb−Free Devices
Applications
• Automotive and Marine Lighting
• Constant Current Source, High Brightness LED Driver
• Low Voltage and Landscape Lighting
NCP3066, NCV3066
NCP3066, NCV3066
Figure 5. Oscillator Frequency Figure 6. Oscillator Frequency vs.
Supply vs. Timing Capacitor Voltage
INTRODUCTION
The NCP3066 is a monolithic power switching regulator optimized for LED Driver applications. Its flexible architecture enables the system designer to directly implement step−up, step−down, and voltage−inverting converters with a minimum number of external components for driving LEDs. A representative block diagram is shown in Figure 3
comparator value, the output switch cycle is inhibited. When the load current causes the output voltage to fall below the nominal value feedback comparator enables switching immediately. Under these conditions, the output switch conduction can be enabled for a partial oscillator cycle, a partial cycle plus a complete cycle, multiple cycles, or a partial cycle plus multiple cycles.
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