NCL2801LED2GEVB ON Semiconductor

NCL2801LED2GEVB Deep Dimming LED Driver 150 W Evaluation Board User s Manual www.onsemi.com EVAL BOARD USERS MANUAL OVERVIEW This manual covers the specification, theory of operation, and NCP13992 LLC for the output converter which testing and construction of the NCL2801LED2GEVB demo demonstrates a 150W LED driver. This LED driver features board. This demo board uses NCL2801 as the front end PFC deep dimming with a 010 V interface. Figure 1. Semiconductor Components Industries, LLC, 2019 1 Publication Order Number: March, 2020 Rev. 1 EVBUM2643/DNCL2801LED2GEVB SPECIFICATIONS Input voltage 90 Vac 305 Vac Output Voltage 50 Vdc Nom. Output Current 1.5 A Max Output Ripple 5% Max Efficiency 94% Max Switching Frequency 85 kHz 140 kHz Dimming Interface 0 10 V Dimming Range 0.3% 100% PCB Size 180 mm 65 mm The key features of this demo board include: delay lowers the switching frequency and can improve efficiency under certain load conditions. Unlike typical CrM High Efficiency boost converters based on voltage mode control, the CrM PFC NCL2801 utilizes current mode control providing more LLC Half Bridge precise operation. A multiplier is required to condition the Dual Dimming Control envelope of the input current waveform. This IC features a Low Standby Power novel multiplier design to deliver very low input current Integrated Thermal Shutdown and UVLO THDi over a broad power range. An offset is introduced to the output of the multiplier to compensate for nonideal THEORY OF OPERATION nature of the process. This function maintains sinusoidal input current waveform especially near the zero crossings of Overview the applied input. Line Feedforward compensation adjusts The NCL2801LED2GEVB has 2 converters. The front the gain of the controller to improve wide range control. end converter is based on the NCL2801 PFC controller and Gain is reduced at high input voltage and increased when the the NCP13992 LLC controller regulates the output current applied voltage drops to a lower level. This gain change to the LEDs. The NCP13992 has hardware handshaking maintains the output of the error amplifier, or VCTR, in a with the NCL2801 to control no load power. At startup, the more desirable operating range away from low level noise NCL13992 provides V to the NCL2801 while also CC and high level clipping. The gain change occurs in the monitoring the HVDC from the voltage divider that sets the unused input voltage band between 150 and 180 Vac. The regulated boost voltage. If the boost voltage does not come change is clearly visible by monitoring VCTR while applied into regulation within 200 ms, the NCP13992 turns off V CC voltage passes through this range. Range change has no to the NCL2801. LLC converters work best when the input effect while operating in typical global mains voltage and output voltage are within a narrow range. The PFC ranges. High power factor converters use low loop provides the regulated voltage for the LLC input. bandwidth to maintain high PF and low THDi performance. As such, response to input voltage or output load changes is PFC typically slow and suffers large deviation from the regulated The front end converter is a CrM boost converter based on value. The NCL2801 features a Dynamic Response the NCL2801 PFC controller. This controller is optimized Enhancer (DRE) which quickly restores the control loop to for high power factor and low THD over a broad range of the required range in response to changes in power. DRE line voltage and loads. The NCL2801 is designed to control maintains the output voltage even during an extreme zero to high power factor boost converters. This description will 100% load change. The DRE function is also active during focus on aspects which have been optimized to provide very initial startup to speed the process of charging the output low THDi and high efficiency. capacitor. This DRE function allows use of smaller and The circuit operates in Critical Conduction Mode (CrM) lower cost output capacitors in place of larger values often for high loads, and transitions to Discontinuous Mode at used to mitigate the effects of load changes. Two Over lighter loads by forcing a dead time. This innovative Valley Voltage Protection (OVP) functions are included in this Count Frequency Foldback method reduces the switching version of NCL2801. The first OVP activates at 105% of frequency while preserving the benefits of traditional CrM nominal output voltage and gradually reduces ontime to operation. The start of the next switching cycle is timed to zero. This reduces the power processing gradually over a the power MOSFET drain voltage ringing after the end of period of time avoiding erratic control of the output voltage. demagnetization which improves efficiency by switching at This function typically manages events like rapid changes in the valley. Internal circuity allows nearunity power factor applied voltage or load. If the output voltage continues to even when the switching frequency is reduced. Introducing www.onsemi.com 2