NCL2801LED1GEVB NCL2801LED1 High Precision 200 W Power Factor Controller Evaluation Board User s Manual www.onsemi.com Evaluation Board Overview EVAL BOARD USERS MANUAL This manual covers the specification, construction, and testing of the NCL2801 evaluation board. This board is configured as a 200 W Power Factor Corrector front end suitable for conditioning the input power of various switchmode power supplies. This board provides high power factor and low total harmonic distortion of input current over the extended input voltage range and very wide output load range. Performance exceeds requirements for many demanding applications including LED lighting, computing power, and white goods products. The Key Features of this Demo Board Very Low THDi Across a Wide Operating Range High Power Factor Fast Response to Dynamic Loading Valley Count Frequency Foldback Improves Efficiency Tight Output Voltage Regulation Two Levels of Over Voltage Protection Brown Out/In Protection Line Feedforward Current Limit Open/Short Pin Protection Table 1. SPECIFICATIONS Input Voltage 100 277 V ac Line Frequency 50/60 Hz THDi (>30% Load) 10% Max. Power Factor (>30% Load) 0.9 Min. Output Voltage 450 4% V dc Output Power 200 W typ. Efficiency (>30% Load, 230 V ac) 95% Min. Ripple 10.5 Vpk Pk Semiconductor Components Industries, LLC, 2018 1 Publication Order Number: October, 2018 Rev. 0 EVBUM2586/DNCL2801LED1GEVB THEORY OF OPERATION response to input voltage or output load changes is typically The NCL2801 is designed to control high power factor slow and suffers large deviation from the regulated value. boost converters. General information on boost converter The NCL2801 features a Dynamic Response Enhancer operation can be found in other literature. This description (DRE) which quickly restores the control loop to the will focus on aspects which have been optimized to provide required range in response to changes in power. DRE very low THDi and high efficiency. maintains the output voltage even during an extreme zero to 100% load change. The DRE function is also active during The circuit operates in Critical Conduction Mode (CrM) for high loads, and transitions to Discontinuous Mode at initial startup to speed the process of charging the output lighter loads by forcing a dead time. This innovative Valley capacitor. This DRE function allows use of smaller and Count Frequency Foldback method reduces the switching lower cost output capacitors in place of larger values often frequency while preserving the benefits of traditional CrM used to mitigate the effects of load changes. operation. The start of the next switching cycle is timed to Two Over Voltage Protection (OVP) functions are the power MOSFET drain voltage ringing after the end of included in this version of NCL2801. The first OVP demagnetization which improves efficiency by switching at activates at 105% of nominal output voltage and gradually the valley. Internal circuity allows nearunity power factor reduces ontime to zero. This reduces the power processing even when the switching frequency is reduced. Introducing gradually over a period of time avoiding erratic control of delay lowers the switching frequency and can improve the output voltage. This function typically manages events efficiency under certain load conditions. like rapid changes in applied voltage or load. If the output Unlike typical CrM boost converters based on voltage voltage continues to rise to 107% of nominal, a second OVP mode control, the NCL2801 utilizes current mode control function stops all switching to avoid a runaway situation. providing more precise operation. A multiplier is required to Switching resumes when the output voltage returns to condition the envelope of the input current waveform. This normal. The OVP functions can be observed during initial IC features a novel multiplier design to deliver very low startup and for large reductions in output load. input current THDi over a broad power range. The CS pin links the switch current to the boost control An offset is introduced to the output of the multiplier to function. This pin also provides over current protection on compensate for nonideal nature of the process. This a cycle by cycle basis. A programming feature is also function maintains sinusoidal input current waveform managed by the CS pin. At initial power up, the NCL2801 especially near the zero crossings of the applied input. outputs a current through the CS pin to read a resistor placed Line Feedforward compensation adjusts the gain of the on the circuit board. A lookup table links the measured controller to improve wide range control. Gain is reduced at resistance to one of six levels. Resistance below 50 high input voltage and increased when the applied voltage nominal is interpreted as a shorted pin, or assembly fault drops to a lower level. This gain change maintains the output which stops the converter from operating. Nominal of the error amplifier, or VCTR, in a more desirable impedances of 150, 330, 620, and 1 k are linked to one of operating range away from low level noise and high level four thresholds determining when the control function clipping. The gain change occurs in the unused input voltage changes from CrM to DCM operation. A resistance band between 150 and 180 V ac. The change is clearly measurement greater than about 1.3k nominal is visible by monitoring VCTR while applied voltage passes considered an open circuit, or assembly fault which disables through this range. Range change has no effect while the converter. This feature allows easy configuration of the operating in typical global mains voltage ranges. operating mode and detects faults on the circuit board. This High power factor converters use low loop bandwidth to EVB is fitted with 150 which invokes the lowest CrM to maintain high PF and low THDi performance. As such, DCM threshold. www.onsemi.com 2