Hello fellow electronics enthusiasts!
I'm planning to build my first SMPS using this transformer : Myrra 74030 and this controller IC: THX 203 .
I have noticed that the voltage range of the auxiliary winding of the 74030 is given as 7 - 14.5 volts. I wanted to use the secondary marked as S3 to create a voltage of 12 V and my input to the primary would be about 230 V AC. If I'm correct under these circumstances the voltage generated on the auxiliary would have been around 10 to 11 V, which is not OK since the ICs internal regulation kicks in at 9.6 V and stops the switching until the voltage drops under this specific voltage.
After considering this, I decided to connect S2 and S3 in series to create a larger secondary winding and using this to create the 12 volts. If I'm correct, taking the newly created turns ratio into account the auxiliary voltage will be 5,3 volts which is OK for the IC, but is lower than the voltage range specified in the 74030's datasheet for the auxiliary winding. Can it cause any problems if I drive the auxiliary winding at a lower voltage than what is recommended in the datasheet?
I'm planning to build my first SMPS using this transformer : Myrra 74030 and this controller IC: THX 203 .
I have noticed that the voltage range of the auxiliary winding of the 74030 is given as 7 - 14.5 volts. I wanted to use the secondary marked as S3 to create a voltage of 12 V and my input to the primary would be about 230 V AC. If I'm correct under these circumstances the voltage generated on the auxiliary would have been around 10 to 11 V, which is not OK since the ICs internal regulation kicks in at 9.6 V and stops the switching until the voltage drops under this specific voltage.
After considering this, I decided to connect S2 and S3 in series to create a larger secondary winding and using this to create the 12 volts. If I'm correct, taking the newly created turns ratio into account the auxiliary voltage will be 5,3 volts which is OK for the IC, but is lower than the voltage range specified in the 74030's datasheet for the auxiliary winding. Can it cause any problems if I drive the auxiliary winding at a lower voltage than what is recommended in the datasheet?