Generally speaking, no matter be the controller of the controller of primary end or sub end, need to be able to negotiate the way that electric segregation has signal is transmitted in two kinds of frameworks, it is opto-coupler normally (or smooth isolator) . However, they can bring a few adverse elements: Their rated temperature is 85°C only normally, electric current is transmitted than (CTR) lets time and change, this means their transmission behavior to be able to produce change during circuit service life; In addition, still need other component to control opto-coupler, if use opto-coupler, the rate of feedback annulus region that keeps apart type power source normally very slow.

 

In recent years, already developed a few concise solutions in the light of this problem, stimulate type controller instead for example, use at needing to undertake electric segregation to power source voltage normally and in outputting the power application under 60W. It does not measure output voltage directly, through monitoring primary end transformer winding the voltage of two end, can get concerned outputting the criterion with enough and accurate voltage actually. Its adjust precision depends on commonly used condition of application, include to input and output voltage, laden change and voltage change.

 

To a lot of application, the ±10% adjustment to ±15% precision is already enough. The graph is shown 1 times for LT8301, as a result of compositive mains switch, use SOT23 to enclose, IC requires very few exterior element only, the segregation puncture voltage of circuit depends on only what use transformer, because this can provide huge flexibility, it is especially when the segregation voltage with very high demand.

 

Graph 1. The LT8301 that need not keep apart feedback method stimulates type manostat instead.

 

Nevertheless, voltage of higher to need output controls the application of precision, still another interesting solution ——ADI faces what the market rolls out to stimulate type controller ADP1071 instead, it includes a complete part that uses ICoupler® technology to become type feedback way, graph the 2 circuit that showed its require element of few amount passive only.

 

ADP1071 includes primary end the controller, sub end that can improve changeover efficiency active commutate controller, and method of feedback of completely compositive type, can realize very quick feedback annulus way. Through employing this solution, output voltage adjusts very accurate, more important is very fast, when although be in,laden twinkling becomes very big not exceptional also, allowable job temperature is as high as temperature of 125°C silicon chip.

 

Graph 2. ADP1071 stimulates type controller to have way of compositive type feedback instead, can realize very accurate adjustment.

 

Its are the biggest segregation voltage depends on place choosing transformer and the segregation technology that IC uses switch manostat, the voltage of the biggest segregation of chip is 5kV, already applied for those who accord with VDEV0884-10 to enhance insulation to classify grade.

 

Two afore-mentioned interesting solutions all can be used at developing electric segregation power source. The basis uses a case, need not feedback the solution of method or the solution that have way of feedback of completely compositive type are appropriate likely, because they accept the restriction of temperature of opto-coupler 85°C job no longer, LT8301 and ADP1071 can realize power density very tall compact model power source design.