Big ox teachs you how to find mains switch return
[introduction] in the power source design in the success, power source layout is among them a the most important segment. But, in how to accomplish this respect, everybody has his viewpoint and reason. The fact is, a lot of different solutions are reach the same goal by different routes; If the design is not true imbroglio, most power source can work normally.
Of course, this also has regulation of a few versatility among them, for example:
Do not run sensitive signal in sudden switch signal. Change character, do not nod next moving feedback to dog in switch part.
Ensure power load dogs and enough of size of ground connection layer supports current electric current.
Maintain a successive ground connection layer as far as possible.
Use enough via (begin with every via 1A normally) , be linked together ground connection layer.
Besides these basic layout regulation, I can identify switch loop above all normally, decide what loop has electricity of high frequency switch next. The graph is shown 1 times to be aimed at step-down power source (principle graph and layout) simplify a give typical examples of power level.
Graph 1: Graph of principle of step-down power source and layout
Two kinds of condition exist in step-down power source (assume conduct pattern continuously) : Control switch (Q1) when when putting through, with control switch disconnects. When control switch puts through, electric current flows to inductor from the input. When control switch disconnects, electric current continues to flow in inductor and shed classics diode (D1) . Electric current is outputted continuously.
But existence inputs pulse electric current, this is the part that you need to pay close attention to in layout. In the graph 1 in, this loop is labelled be ” of “ high frequency loop, show with blue. The first goal of your layout is Q1, D1 and input capacitance and loop of inductance of the shortest, lowest join. This return is less, the noise that switch produces is jumped over low. If oversight this, power source general cannot work effectively.
The regulations that identifies switch loop applies to all power source develop to attack structure. Each measure of regulations are respectively:
● is in put through condition decides voltaic access.
● is in disconnect condition decides voltaic access.
● finds the place of permanent current.
● is found intermittent voltaic position.
● decreases as far as possible intermittent voltaic annulus road.
Listed in this list the crucial return that gives power grading place:
● step-down —— inputs capacitance loop.
—— of ● step up outputs capacitance loop.
● turns over photograph step-down – input of step up —— and loop of output electric capacity.
● stimulates —— input and loop of output electric capacity instead.
● Fly-Buck™—— inputs capacitance loop.
● SEPIC—— outputs capacitance loop.
● Zeta—— inputs capacitance loop.
● is being stimulated, capacitance of input of —— of half bridge, complete bridge circulates.
No less than of power source layout a kind of artistic form is common, everybody has his kind, and a lot of moment also can have effect. Need ensures is, when you determine the spare parts position of power level, determine return of high frequency switch above all; Such you can be oneself spare time, avoid embarrassment.