| Electronics > Beginners |
| SMPS chip but not for 240V? |
| << < (3/7) > >> |
| oPossum:
If it has one switch it is probably flyback. If it has two switches (or a multiple of 2) it is probably forward. Switch refers to whatever is doing the switching - BJT, MOSFET, IGBT |
| FriedMule:
--- Quote from: MosherIV on September 04, 2019, 06:47:11 am ---Hi. Typically mains voltage smps rectify the mains AC into a high voltage cap. This HV DC is pulsed into an isolation transformer at high freq. The freq controls the output voltage/current. The output V needs low ESR caps to smooth the output of the isolation transformer. The output voltage is monitored and fed back via an opto isolator. This feedback is used to determine the freq to pulse the isolation transformer. This is all controlled by a ASIC which is powered striaght from the HV DC. I think (but I am not sure) this is the 'forward converter' topology. --- End quote --- Yes thats sounds logical, and like the attached drawing. But In my book it looks like that 240V is connected to the chip? |
| oPossum:
--- Quote from: FriedMule on September 04, 2019, 06:46:43 am ---Do you mean a transformer before the SMPS circuit? --- End quote --- See figure 1 in the FSL137 data sheet. |
| oPossum:
--- Quote from: FriedMule on September 04, 2019, 06:53:00 am ---But In my book it looks like that 240V is connected to the chip? --- End quote --- That is for a bootstrap circuit that gets the chip running. Operational power comes from the transformer winding. |
| FriedMule:
--- Quote from: oPossum on September 04, 2019, 06:53:26 am --- --- Quote from: FriedMule on September 04, 2019, 06:46:43 am ---Do you mean a transformer before the SMPS circuit? --- End quote --- See figure 1 in the FSL137 data sheet. --- End quote --- So the 240V does not go undisturbed down to the HV-pin at the chip? |
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