SMPS Design Support

Posted by: Rachit Dave on 03/19/2013

Hello,

We have designed an SMPS for 18W(9V,2A) . We have used PI Software for the solution. Presently we are getting the required output from the solution. But after switching off the SMPS it does not gets discharged fully. It shows voltage of around 1.4 V. Please do guide us if we are going wrong somewhere.

Waiting for your reply.

Regards

Rachit dave

Files

TNY_278_9V_2A_Design4_0.pdf (68.61 KB)

Comments

Because the power supply has no dummy load on secondary side, so the 27000uF output cap discharges very slowly. Put a dummy load can solVe this problem easily. 20k to 100k dummy load can improve this issue a lot. Another solution is use less output cap. But you have to make sure that the ripple and noise is good with low value output cap.

Regards

Thanks for the reply.

We tried placing the pre-load resistor and our SMPS gets fully discharged. But we are facing another issue. When we switch off the mains and whithin the discharging period if we again switch on the mains the smps do not reach the required output of 9V. The smps output increases output very slowly.

Waiting for your reply.

Regards

Rachit Dave

Could you upload waveforms of output voltage, drain voltage and drain current when the issue happen?

Thanks