Heating on VIPER22ADIP-E

[Pemendra]

Hi STMicroelectronics team,

I am using VIPER22ADIP-E to design 15V, 5W power supply with input supply of 230Vac with diode bridge rectifier.

The schematics file is attached here,

When i am loading it with 5W load, the IC  VIPER22ADIP-E is get heated and frequently turning off due to internal thermal protection. However, IC's power rating is recommended up to 12W (for US i.e. 85-265Vac) and  20W (European i.e. 195- 265V) is provided in datasheet.

What is wrongs in design? 

Please suggest solution.

 

Thanks and Regards

Pemendra Kumar Pardhi

Sr. Design Engineer

CastNX Pvt. Ltd. Dewas 

[Peter BENSCH]

Welcome @Pemendra, to the community!

The performance class specified in the data sheets refers to the normally intended topology, i.e. flyback in the case of the VIPER22ADIP-E. In your design, however, you are implementing a non-iso buck regulator that does not reduce the input voltage via a transformer, but can only do so via the duty cycle. In this case, however, quite high peak currents occur that can lead to overheating. For this reason, such a regulator in buck topologies achieves only a fraction of the otherwise specified performance.

You could build a flyback that can deliver considerably higher power with the VIPER22ADIP-E. You can also realise non-iso flyback with smaller VIPER, where you can do without an isolated feedback and thus save costs - only the transformer is the additional expense.

Hope that helps?

Regards
/Peter

[Pemendra]

Hi, @Peter BENSCH ,

Thanks for reply and suggest an alternate topology.

[Peter BENSCH]

As mentioned you could use a non-iso flyback, like e.g. the STEVAL-ISA196V1. This is designed for 5V, but can easily be redesigned to e.g. 15V (different secondary winding, smaller Schottky diode D3, adapted passive components C9...C11, L2, R6).

Hope that helps?

Good luck!
/Peter