Power supply circuit for Smart Energy Meter

Hi Team,

Any update on this?

Hi marisa54,

Your inquiry has already been delegated to the support group. We'll get back to you the soonest possible time.

Thanks and regards,

PI-Lupin

Hi Lupin,

Looking forward for your response. We need isolated 3.3V DC output for Microcontroller and line referenced 5V DC for energy meter IC. So, totally we need two outputs from flyback SMPS.

Thanks and regards,
Ramesh

Hi marisa54,
What is the input voltage range for this design? I assume tolerance for 3V3 is tight, or ~1%. Is 5% tolerance OK for the 5V0 line-reference output? Do you have any details on the minimum load for the 5V0 output? We can use LNK-XT2's LNK3604 for this design.
Regards,

Hi BERJ,

The input range is (85-265)V AC, 3V3 is tight tolerance (~1%). 5% tolerance is Okay for 5V0.
The 5V power supply is for energy meter IC and few optocouplers. The minimum load will be around 15-20mA.

The 5V should be reference to AC line (Non-isolated) because Shunt resistor connected in AC line. 3V3 should be isolated.

Thanks and regards,
Ramesh

Hi Team,

Any update on this?

Hi Ramesh,
We have not yet released a Design Example Report (DER) but we have done internal designs for this application. Attached sample schematic should be a good start and how the design should look like. Primary bias winding circuit (D10, C15, R7) may not be needed if you are not concerned with no-load conditions. L3 and C10 will be required for low ripple at the 3V3 output. R8 may not be required if minimum load for 5V is guaranteed.
You can check AN86 for the design guide and tinker with PIExpert for the component stresses and transformer design.
Regards,

Hi BERJ,

Thank you for your support and time. I will proceed with your circuit

Thanks & Regards
Ramesh