This application note describes the functioning of the STEVAL-ILL026V1 non-isolated 3 W offline LED driver power supply designed using the VIPER22A-E low power offline SMPS primary switcher from STMicroelectronics. The circuit regulates the load current to 350 mA and generates about 10 V. The load is composed of three high-brightness (HB) LEDs, connected in series. The project does not provide safety isolation between the input and output. This document provides the power supply specification, circuit diagrams, the complete bill of materials, and reports the results of circuit testing.
AN2941 is an application note released by ST company, which mainly introduces the application characteristics of L6563S and L6566A two chips, suitable for 75W adapter design. This application note introduces the characteristics of the two chips, circuit principle, efficiency measurement, harmonic content measurement and function check.
AN2938 Application note introduces the demonstration kit based on the PM6686 dual step-down controller with adjustable output voltages and adjustable LDO for notebook power systems.
PM6686 is a dual step-down controller with adjustable output voltages, adjustable LDO and charge pump circuit for notebook power systems. This application note describes the PM6686 demonstration kit, which represents a typical application circuit, and allows testing of all the functions of the PM6686 device. The demonstration kit provides two switching sections with 5 V (OUT1) and 3.3 V (OUT2) outputs from 8 V to 28 V input battery voltage. The operating switching frequency of the two sections is 400 kHz and 300 kHz, respectively. Each switching section delivers more than 5 A of output current. An internal linear regulator can provide 5 V at 100 mA peak current. The charge pump circuit provides an auxiliary 12 V output voltage.
This application note presents the circuit diagram and design details of the VIPER27LN demonstration board, which provides a wide range input voltage (90 V-265 V) and 5 V-12 W output power for auxiliary power applications in consumer applications such as LCD or plasma TVs, some models of DVD recorders, set-top boxes with hard disk, as well as desktop computers.
This application note describes, step-by-step, all the principles and calculations used for a modified buck converter intended for high brightness LED applications. The converter is designed as a constant current source to achieve the best lighting performance from the LEDs.
This application note focuses on the design of a flash LED driver using the STCF05 device, which is a boost current mode converter with an I²C interface and internal current source. The schematic, functional description, recommendations for PCB layout, and external component selection are also discussed in this application note. The STCF05 device is designed to drive two LEDs in series with a total forward voltage range from 5.3 V to 10.2 V.
This document introduces the LED current source based on L5973AD and the basic principles and applications of LEDs. The brightness of LEDs is proportional to the forward current flowing through them. LEDs can be divided into low current LEDs and high current LEDs based on the typical forward current of the final application. The voltage drop across LEDs varies widely, so current mode driving is more convenient. The current source regulates the LED current and the output voltage is determined by the forward voltage of each LED.
The PM6675S device is a high-efficiency step-down controller with an embedded 2 A LDO linear regulator. The constant on-time (COT) architecture assures fast transient response supporting both electrolytic and ceramic output capacitors. An embedded integrator control loop compensates the DC voltage error due to the output ripple. Selectable low-consumption mode allows the highest efficiency over a wide range of load conditions. The low-noise mode sets the minimum switching frequency to 33 kHz for audio-sensitive applications. The LDO linear regulator can sink and source up to 2 Apk. Two fixed current limits (±1 A and ±2 A) can be chosen. An active soft-end is independently performed on both the switching and the linear regulators outputs when disabled.
The PM6675AS is a high-efficiency step-down controller with an embedded 2A LDO regulator. It features fast transient response, selectable low-consumption mode, and low-noise mode.
