![]() ![]() Used for the ECDL Driving Licence examinations. ![]() Reference management software package, used to manage bibliographies and references when writing essays and articles.ħ-Zip is a file archiver with a high compression ratio.ĭesigned to view, create, manipulate and manage files in Adobe's Portable Document Format (PDF). See here for changes coming to ArcGIS - AnywhereĪrcmap city engine, student home use, data loaderĭesigned to view, create, manipulate and manage files in Adobe's Portable Document Format AnywhereĪ fully-interactive visualization and analysis of crystal and molecular Anywhere MATLAB s a high-level language and interactive environment that enables you to perform computationally intensive tasks faster than with traditional programming languages such as C, C++, and Fortran. Ibm, amos, Sample, Power, pasw, Student home use For more information, please see PMP10900.# A A B B C C D D E E F F G G H H I I J J K K L L M M N N O O P P Q Q R R S S T T U U V V W W X X Y Y Z Z NameĪ statistical Package, designed for analysing data. Careful design considerations will yield a low-noise, stable power supply. The two-stage filter is a popular way to reduce the output ripple of a buck converter. Figure 2 shows the measured loop response.įigure 2: 5Vin, 3.3Vout at 5A loop responseįigure 3 shows the ripple after the second stage – well below 1mV. In this example, 25kHz bandwidth is sufficient. I recommend rolling the power supply off low enough to prevent the second resonance from crossing back over zero and maintaining greater than 10dB of gain margin. Simulating the power-stage gain and phase shows the output pole at 6.5kHz. The second and final step is to compensate the power supply using current-mode control for simplicity. Also notice 39dB more attenuation at the 750kHz switching frequency measured after the second filter. There are two resonances: 25kHz and 150kHz. By choosing a second resonance of 150kHz, Equation 1 can be used to calculate the second inductor.įigure 1: Schematic and transfer functionįigure 1 shows the schematic and transfer function before and after the second LC. A 100♟ 6.3V X5R ceramic capacitor is used for the second-stage capacitor in the example. Smaller capacitances will push the second resonance away from the power-supply loop bandwidth, while larger capacitances increase attenuation but potentially interfere with the control loop. The first step is to choose a second-stage capacitor approximately four to 10 times the first stage capacitance. 31dB of attenuation is needed at the switching frequency to reach 1mV of output ripple. The calculated output ripple is 39mV, mostly due to the limited capacitance of 7.2♟ from DC bias. ![]() In this example, we will walk through the design of a 5V-input 3.3V/5A power supply with a <1mV ripple specification.įor simplicity, let’s start with a single-stage 750kHz switcher designed with a 1µH inductor and one 22♟ 6.3V X5R ceramic output capacitor. If designed properly, the two-stage filter can meet very tight power-supply noise requirements. Designers may be forced to use a two-stage LC filter in order to achieve output ripple levels in the sub-5mV range. Even with low equivalent series resistance (ESR) ceramic output capacitors, it is often impractical to use a traditional single-stage inductor-capacitor (LC) filter to power such loads. Many applications require low-noise power supplies, including laser-diode drivers and optical modules. ![]()
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