I am testing the following power supply which steps down from 230VAC to 12VDC.
When testing without T1 and supplying 39VDC instead of the rectifier, the switch-mode power supply (TPS5401) outputs 12V and 50mA can be drawn continuously. When testing with T1 and the bridge rectifier, the bridge rectifier outputs 39VDC and unloaded the switch-mode output is 12V but upon trying to draw 50mA from the 12V, the output drops to around 2V with the bridge rectifier remaining at 39VDC. How can I ensure that the transformer is suitable for my current draws?
- 230V-15V AC, 1.8VA. Measured (unloaded) : 28.2V AC
- For 230VAC, no load peak voltage, Vsec peak = 35.5V
- For 230VAC, full load peak voltage, Vsec peak = 19V at 70 degrees Celsius