This article mainly introduces onsemi's 75 W solution based on the NCL35076 continuous conduction mode (CCM) DC-DC buck controller and the 100 W and 240 W solution based on the NCL30076 quasi-resonant (QR) buck controller. Typical applications of the two solutions are LED lighting systems, analog/PWM dimmable LED drivers, with a wide analog dimming range from 1% to 100%.
ON Semiconductor’s proprietary LED current calculation technology and the zero input voltage offset of the internal detection and feedback amplifier can perform accurate current stabilization within the entire analog dimming range. The current stabilization accuracy is <±2% at full load and at 1% <±20% under load. Excellent dimming characteristics can be switched between CCM (NCL35076) or QR (NCL30076) and discontinuous conduction mode (DCM) according to load conditions, thereby ensuring low LED current ripple to provide higher energy efficiency, such as heavy load Work in CCM (NCL35076) or QR (NCL30076), and work in DCM at light load. Low standby power consumption in standby mode. PWM dimming is also provided to maintain a constant LED color temperature. NCL3X076 soft start function realizes steady-state start without overshoot. Various protection features such as VDD overvoltage protection (OVP), LED short circuit protection (SLP), overcurrent protection, and thermal shutdown protection (TSD) ensure high system reliability. Among them, the NCL35076 CCM 75 W solution has the advantage of a small form factor. The NCL30076 QR 100 W solution has high energy efficiency at high voltage input.
The NCL30076 QR 240 W solution uses ON Semiconductor’s NCL2801CDA PFC driver, NCL30076 step-down driver, NCP10671 switch driver, and a dimming signal controller. NCL2801CDA is a current-mode CrM boost PFC controller that utilizes ON Semiconductor’s total harmonic distortion (THD) enhancement technology to provide best-in-class THD performance over a wider operating range. The valley counting frequency foldback (VCFF) method optimizes energy efficiency and standby power consumption. NCP10671 integrates a fixed frequency current mode controller and 700 V MOSFET, with high integration, including soft start, frequency jitter, short circuit protection, cycle skipping, slope compensation, and dynamic self-powered (without auxiliary winding). During a nominal load operation, NCP10671 switches at one of the available frequencies (60 or 100 kHz). When the output power demand decreases, the IC will automatically enter the skip cycle mode to reduce standby power consumption. Protection functions include a timer to detect an overload or short-circuit events and over-voltage protection with automatic recovery. NCP10671 has optimized standby performance, connects auxiliary winding or supplies power to IC from the output, stops DSS work, and helps reduce input power consumption at high voltage to less than 15 mW.
Accurate steady flow and wide analog dimming
In addition, the steady current accuracy and simulated dimming range test conditions and results of the NCL35076 CCM 75 W evaluation board and NCL30076 QR 100 W evaluation board are as follows:
NCL35076 CCM 75 W evaluation board:
VOUT (50/30/10 V), the inductance value is typically ±20%, the temperature (-10/25/90degree), 27 dimming curves have been tested, and the current stabilization accuracy is ± 1.5% at full load. It is ±10% at 1% load, and the analog dimming range is <1%.
NCL30076 QR 100 W evaluation board:
VOUT (300/200/100 V), the inductance value is typically ±15%, the temperature (-10/25/90degree), 27 dimming curves have been tested, and the steady current accuracy is ± 2% at full load. It is ±14% at 1% load, and the analog dimming range is <1%.
Energy efficiency test
The test conditions and energy efficiency curve of the evaluation board are as follows. The energy efficiency of the NCL35076 CCM 75 W evaluation board at 10 V, 30 V, and 50 V can be as high as 92%, 96%, or more than 98%. The energy efficiency of the NCL30076 QR 100 W evaluation board at 100 V, 200 V, and 300 V can exceed 96, respectively. %, 97% and close to 98%.
NCL30076 QR 100 W: VIN: 400 VVOUT: 100/200/300 V dimming: 10~100% working time: 30 minutes NCL35076 CCM 75 W: VIN: 60 VVOUT: 10/30/50 V dimming: 10~100 % Working time: 30 minutes
Thermal performance test
We tested the input voltage Vin 60 V, Vout 50 V, Iout 1.5 A, and the NCL35076 CCM 75 W evaluation board showed good thermal performance when it worked for 30 minutes. The input voltage Vin 400 V, Vout 300 V, Iout 0333 A, NCL30076 QR 100 W evaluation board also showed good thermal performance when it worked for 30 minutes.
Summarize
ON Semiconductor’s NCL35076 or NCL30076-based dimmable LED lighting step-down solution has the advantages of high energy efficiency, high precision, and high reliability, with an analog dimming range as low as 1%, proprietary LED current calculation technology and internal detection and feedback The amplifier's zero input voltage offset makes the current stabilization accuracy <±2% at full load and <±20% at 1% load. PWM dimming is also provided to maintain a constant LED color temperature. Rich protection features ensure high system reliability. Energy-efficient and intelligent LED lighting is an integral part of ON Semiconductor's intelligent power supply and will help achieve sustainable development.
