Small and medium-sized switching power supply based on NCL30000 - Power Circuit - Circuit Diagram

Full range of MOS power ICs

Domestic probe switch needle KG-300K with a needle head diameter of 3.0mm, normally open switch needle

Integrated inductor

The NCL30000 is a compact controller designed for single-stage PFC LED drivers, ideal for applications ranging from small to medium power levels. It boasts an impressively low startup current of 24µA and an operating current of just 2mA. With cycle-by-cycle current protection and the ability to provide a 500mA current source, it is primarily used in LED driver power supplies, commercial and residential LED decorative lighting, and PFC constant voltage power supplies. This article delves into the key features of the NCL30000, including its block diagrams, simplified application block diagrams, and simplified flyback application block diagrams. Additionally, we'll explore the circuit diagram and bill of materials (BOM) for the NCL30000LED2GEVB evaluation board. The NCL30000 is specifically designed as a switch-mode power supply controller for low to medium power single-stage power factor (PF) corrected LED drivers. It operates in critical conduction mode (CrM) and is compatible with both flyback and buck topologies. In CrM, the switching frequency adjusts dynamically with line and load conditions, resulting in lower switching losses since the current reaches zero before the main MOSFET switch is reactivated, minimizing recovery losses in the output rectifier. The device includes a programmable on-time limiter, zero current detection sensing block, gate driver, transconductance error amplifier, and all necessary PWM control circuitry and protection functions to implement a CrM switch-mode power supply. With a low startup current, it enables fast, low-loss charging of the VCC capacitor. The current sense protection threshold is set at 500mV to reduce power dissipation in the external sense resistor. To ensure reliable performance across a wide range of solid-state lighting environments, the device is specified to operate within a junction temperature range of -40°C to 125°C. Key Features of NCL30000: - Very low 24µA typical startup current - Constant on-time PWM control - Cycle-by-cycle current protection - Low current sense threshold of 500mV - Low 2mA typical operating current - Totem pole gate driver capable of sourcing 500mA and sinking 800mA - Reference design for TRIAC and trailing-edge line dimmers - Wide operating temperature range - No input voltage sensing requirement - Enable function and overvoltage protection - Lead-free, halogen-free/BFR-free, and RoHS compliant Typical Applications of NCL30000: - LED driver power supplies - LED-based downlights - Commercial and residential LED fixtures - TRIAC-dimmable LED-based PAR lamps - Power factor corrected constant voltage supplies Figure 1: NCL30000 block diagram Figure 2: Simplified NCL30000 application block diagram Image 3: Simplified Flyback Application Block Diagram: Secondary Constant Current Control