may be output capacitance is too large and soft start time of TOP not enough for complete charge of it
in your schematic you are using a 47uF control pin capacitor. That initially gets charged up to 5.8v by the internal startup circuit…….that 5.8v then gets used to start the converter up…however, if the converter does not get started before the control pin capacitor has discharged to 4.8V then the controller just trips out because it assumes that there is an overload or short circuit on the output.
You could try remving some output caps and try again…..does your control pin stay above 4.8V during the startup?
You might be able to use the power integrations recomended "soft-finish" circuit in order to start up with such large capacitance...search their site to see it.
...or just remove a load of that capacitance and try again.
- - - Updated - - -
Treez:
As per the PI Application note:
In addition to the 100 nF capacitor connected to the CONTROL
pin, a series combination of a 6.8 W resistor and a 47 mF
electrolytic capacitor is required to be connected between the
CONTROL pin and the SOURCE terminal of the TOPSwitch-JX.
The 47 mF capacitor acts as an energy reservoir and provides
power to the TOPSwitch-JX internal circuitry during start-up
Now who will make it go 4.8v..??
Dear All
Here i am using a TOP271 for my Project of output 12v 8amp.
it turns on no load giving me a 12.3v output also if i put the load it also draw 8 amp of current.
but if i attached load previously and trying to turn on smps it is not giving output.
Help me with remedy.View attachment 127765View attachment 127766
- - - Updated - - -
Condition1: If i turn on smps with no load i am getting output 12v then i will have to put the Load of 8 amp it also draws the same.
Condition 2: If i attached load to the output and try to turn on smps it does not Turn on.
WHY this is happening..??
Schematics attached in above post.
"what is resonant frequency of the output LC filter.?..."
Is this a general rule for all topologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?