ripple and current limit
Posted by: mehmetekici
on
Hello,
We have used PI expert for a power supply design. We have nearly 1V of ripple and worst than it it has 90-130khz periodic sinusoid time to time through the filter.
You can see the schematic enclosed.
Regards,
Files
5V8, 2A5.pdf
(18.58 KB)
Comments
We had in stock. We also have 3V9 volt %5 tolerance zeners, Do you think using them is ok or we should change the design to TL431?
Our design need 2.5Amps for duration of 40ms and drops to 0.5amps. We also have got a GPRS module do you think we must use EMC shield wirings at the transformer ?
regards,
I forgot to mention the is a requirement while 2.5A is drown the voltage drop should be less then 200mV but we are seeing much more. Would you suggest anything for it ?
Regards,
Use the TL431.
Why are you using such a small zener? You should use a 4.7V zener. This will mean you need a smaller value resistor in series with the optocoupler which reduces DC gain. This can be why you are seeing poor ripple at the output.
Try the 4V7 zener instead...
Also at this current level I'd use the TL431 for regulating the output.