How To Design A Suitable Power Supplyfor Now An Electronic System

PRLog (Press Release) - Dec 04, 2009 -
Q1: How to evaluate a system's power requirementsAnswer: For a practical electronic system, to a serious analysis of its power requirements. Is not just concerned about the input voltage, output voltage and current, but also careful consideration of the total power consumption, power to achieve efficiency, the power part of the transient response to load changes in the ability, the key components of the tolerance range of power supply fluctuations and the corresponding allowed power supply ripple, as well as heat dissipation problems, and so. http://www.bestlaptopbattery.co.uk/acer/batbl50l6.htm
Power and efficiency are closely related, high efficiency, and in the case of the same load

power consumption less total power consumption for the overall system power budget is very favorable, and contrast LDO and switching power supply, switching power supply efficiency is higher. At the same time, assess the efficiency, not just look at full-load efficiency when the power circuit, but also concerned about the time when light-load efficiency levels.As for the load-transient response capability, for a number of high-performance CPU applications will have strict requirements, because when suddenly start running CPU heavy tasks, you need to start current is great, if the power circuit to respond fast enough, resulting in an instant voltage drops too low, causing CPU to run error.In general, the actual value of the power required for the nominal value of more than + -5%, so it can be calculated accordingly to allow the power supply ripple,http://www.bestlaptopbattery.co.uk/acer/travelmate-4200.htm

of course, to allow a margin of.Cooling problem for those high-current power supply and LDO is more important, by the calculation is also possible to assess whether appropriate.Q2: How to choose an appropriate power supply circuit implementationAnswer: According to analysis of system requirements derived from specific technical indicators, you can choose the appropriate power supply circuit implementation of the. General for the weak parts, including the LDO (linear power converter), switching power supply capacitor step-down converter and switching power supply inductor capacitor converter. In contrast, LDO design the most easy to implement, the output ripple is small, but the drawback is that there may not be high efficiency, heat large, can provide much more current than switching power supply. The switching power supply circuit design flexibility, high efficiency, but the ripple is large, to achieve more complicated, more cumbersome to debug and so on.Q3: How to select the appropriate switching power supply circuit components and parametersAnswer: a lot of unused switching power supply design engineers to produce a certain fear that it would be psychological, such as worry about switching power supply interference, PCB layout issues, components of the parameters and type selection problems. In fact, as long as the understanding of the use of a switching power supply design is still very convenient.Switching power supply typically includes a switching power supply controller and the output of two parts, and some controller will be integrated into the chip to the MOSFET, so that even simpler to use, but also simplifies the PCB design, but reduces the flexibility of the design a little.Switch controller is basically a closed-loop feedback control system, so usually there is a feedback output voltage sampling circuit and feedback loop control circuit. Therefore, this part of the design is to ensure accurate sampling circuit, as well as feedback to control the depth, because if the feedback loop response is too slow, then the transient response capability is there will be many affected.And the output part of the design consists of the output capacitor, output inductor and the MOSFET, etc. These choices are basically to meet a balance between performance and cost, such as a high switching frequency, you can use a small inductor value (meaning a small package and low cost), but the high switching frequency will increase the interference and MOSFET switching losses, thereby reducing efficiency. The use of low switching frequency will result in is the opposite.For the output capacitor ESR and MOSFET's Rds_on parameters is also very critical, a small ESR can reduce the output ripple, but the capacitance will increase the cost, a good capacitor will be expensive Well. Switching power supply controller drive capability should also pay attention, excessive MOSFET can not be a good driver.In general, switching power supply controller vendors provide a specific formula and the use of options for engineers to learn from.Q4: How to debug switching power supply circuitAnswer: there is some experience to share to everyone1: The power output of the circuit's output resistance received by low-resistance high-power panels, so that not the case of resistance welding can be done before the first power supply circuit debugging, to avoid the back of the circuit effects.2: Generally speaking, switch controller is closed-loop system, the deterioration of the situation if the output exceeds the scope of the closed-loop control, switching power supply will not work properly, so this situation will require careful inspection feedback and sampling circuits. Especially if using a large value of the output capacitor ESR will produce a lot of power supply ripple, which will also affect the switching power supply work.Grounding the discussion of technology

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