Low power Universal volatge input SMPS (18-265V)

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hello sir,

I'm designing a universal voltage input SMPS (Flyback topology)
voltage input : - 18-265V
power output : - 7W

Do you have any TOP switch which supports my specifications, if yes please provide me a reference schematic (i am asking for reference schematic since because i couldn't get it through online PI tool, it was not taking 18-265V voltage input).

I am ok with any switch that suits with my specifications. please suggest....

Hi Santosh_JVS,

This is for what application? Then what is the output voltage requirement?

For PIExpert the minimum input voltage limit is 25VAC for TopSwitch IC. Lower input voltage such as 18VAC will give you higher duty cycle that will exceeds the maximum duty ratio of TOP Switch IC, the design must be at least 70% maximum duty. In order to reduce the maximum duty cycle, larger bulk caps is needed (minimum of 680uF), operation is in discontinuous mode (adjust KP to be greater than 1), reflected voltage must be reduced in the range of 60V to 80V. Following the optimization will require usage of larger transformer. Of course the resulting parameters must be bench tested and see to it that aside from can continuously run, at extreme ends of the limit no abnormalities in operation and waveforms shall took place. The topology is flyback.

One solution that you can take a look at is PI design example with reference number DI-152. This utilized TinySwitch-III IC TNY280P in a typical flyback topology. This design example is the same as your input 18VAC to 265VAC. 5V is the output voltage with output power of 3W. Again due to maximum duty cycle specification of the IC (typical DMAX is 65%), the maximum output power is limited. Then using TinySwitch the minimum drain voltage is 50V, in order to operate at lower input voltages, an externally fed charge current (current source circuit) to the BYPASS pin will serve as the start-up circuit of the IC providing approximately 600uA over the complete input voltage range.
You can review the design ideas mentioned on DI-152 that can be seen in PI website under reference design.

If you already has an experience in power supply design, you can also try to use PIXls instead of PIExpert. You can see this also in the same selection menu as PIExpert. Just select PIXls instead of PIExpert. PIXls spreadsheet is the same as excel spreadsheet, but no schematic generation only the parameters value and transformer design drawing and recommendation.

Thanks.

This is for Relay application.

If you not able to provide schematic for 18-265V power supply.

can you provide me simulation module of your top switch so that i can simulate for different input voltage and design for the same...

Hi Santosh_JVS,

I can provide you a schematic using TinySwitch-III 18VAC - 265VAC input with 3W output.
Actually you can try PIExpert using TOP SWITCH with 25VAC input and your desire output. It will generate schematic. Do you want to try?

What is your desired output voltage? 12V for relay supply?

Thanks

Hi PI- MarcusJoaquin,

I am also looking for the similar kind of IC's.
Presently I am using LNK4003D IC's in one of the metering product from last 5 year.
For my new product development I am looking towards new IC which should be suitable for below specification.
Vin = 12V to 400V AC/DC
Supply Frequency = 50Hz, 60Hz or 400Hz
Vout = 10V
Iout = 200mA

This power supply basically I will use for relay driving purpose and I have 12Vdc to 125Vdc auxiliary power supply and 65Vac to 440Vac service mains supply. The SMPS should be work on both power supply.
Please suggest me IC's and schematic.

I choose LNK306D with MOSFET based series voltage regulator circuit from my experience.

Hi PI- MarcusJoaquin,

I am also looking for the similar kind of IC's.
Presently I am using LNK4003D IC's in one of the metering product from last 5 year.
For my new product development I am looking towards new IC which should be suitable for below specification.
Vin = 12V to 400V AC/DC
Supply Frequency = 50Hz, 60Hz or 400Hz
Vout = 10V
Iout = 200mA

This power supply basically I will use for relay driving purpose and I have 12Vdc to 125Vdc auxiliary power supply and 65Vac to 440Vac service mains supply. The SMPS should be work on both power supply.
Please suggest me IC's and schematic.

I choose LNK306D with MOSFET based series voltage regulator circuit from my experience.

Hi Nitesh,

Just to clarify your design requirements.
The input voltage of the power supply you are developing shall work both on AC and DC with minimum input voltage of 12Vac and 12Vdc and maximum input voltage of 400Vac and 400Vdc?

Or you will have two inputs just similar with products used in telecommunication. One is AC input with 65VAC to 400VAC and another is DC input with 12VDC to 125VDC?

Thanks!

Hi,
Thanks pi team.
Yes. you have capture my all requirement.
I am looking for the solution.

Hi Nitesh,

For your requirements of maximum input voltage of 400Vac, I can recommend a Non-Isolated Buck Converter using LNK3296 IC. This is a LNK-TN2 IC with 900V integrated MOSFET in the IC.
It can power-up with a minimum input of 17Vac but need to test if it can start-up with a 2W output power (your requirement is 10V/0.2A).
We will be limited by the maximum duty cycle of the IC, as I already mentioned in my previous comment.
There are design examples provided in PI website such as DER-845. This design implements LN3296, though the input voltage is only at 85Vac, we can decrease that by redesigning the buck inductor and increasing the input or bulk capacitor in order to run at a much lower input voltage.

Thanks!

Hi Nitesh,

To supplement our recommendation of using LinkSwitch-TN2 IC in your design, I attached the schematic for your reference using LNK3296G/P IC for your reference. The circuit was able to power up at 12Vac input but the output power capability is at 900mW with 10V output. While at 16Vac input, we were able to achieve 2W output. This is possible by increasing the bulk capacitance with a total value of 440 uF, this is to maintain the sufficient supply voltage on to the IC even at lower input voltage. You can try this circuit and see if it suits your requirements.

Hi Santosh_JVS,
You can also have this as a reference in your design.
My other suggestion is by using TinySwitch IC, see my previous comment which can operate at 18Vac with 3W output in Flyback topology.
This one is much simpler using LinkSwitch-TN2 IC LNK3296G/P implementing non-isolated buck topology.
The result is at 18Vac input, the output power delivery is also 3W. And since your maximum input voltage is only 265Vac, you can replaced the bulk capacitor with a single electrolytic capacitor with 470uF value rated at 400V.

Hope this would help you designing your power supply using PI IC. Thanks!

Hi MarcusJoaquin

Thanks for 3W design. LNK3296G/P design also i checked though its good design in my application it may not be used. I will be using 3W design in my product.

I was looking for a small 10W watts( low power, low cost) power supply design.
Two output 5V 1.2A & 5V 0.8A
Input 18-265V
Isolated output

can you please provide me a reference schematic for above specs......
by using any of PI switchs (low cost)....

Hi Santosh_JVS,

10W is a bit higher for ultra wide input voltage particularly having a vey low input voltage of 18Vac.
You need a higher input voltage to meet the 10W operation or integrate a front-end circuit to boost the input voltage to a desired voltage input voltage that can provide 10W then turn-off the front-end boost when the input voltage is high enough to provide 10W.

Hi MarcusJoaquin
thanks for your valuable suggestions sir, I had thought of using higher-value input capacitance for this issue but my application is Numerical relay which needs a minimum of 8-10W.
I accept your suggestions.
please help me if you have any design suggestion on this if yes do share the schematic.

using PI switch it will helpful.

Hi Santosh_JVS,

We will try to look for other solution if we do have an IC that is capable with an 8W to 10W output at 18Vac.
But as I've said your output power is already very high for TinySwitch and LinkSwitch IC at a very low input voltage of 18Vac. We will be limited by duty cycle and minimum on-time.

Thanks!

Hi MarcusJoaquin

Actually i checked some TOP switch which are capable for my application. can you try it sir by using TOPswitch but i need to be ensconce on cost.

my actual system required rating : 7W (max 8-10W)

Hi Santosh_JVS,
Same thing with TOPSwitch, the duty cycle will be higher than the specification of the IC and a very high input capacitor is needed.
I am checking another IC, I think this one is maybe suitable or can deliver your requirements.

Hi Santosh_JVS,

As previously discussed, here's another reference that you can take a look at.
You can try to use InnoSwitch3 IC and we do have a design example or a reference design which you can find in PI website.

Please find DER-907Q, the input of this is 30VDC to 550VDC with 12V and 20W output.
At 30VDC, it can powered-up up to 10W, basically 30VDC is equivalent to 21VAC.

Just use a high voltage DC source first to power up this design example.
- Power-up the power supply at 30VDC at no load and gradually increase the load to 10W.
- When already powered up, gradually decrease the input voltage from 30VDC to 25VDC
(equivalent of 18VAC).
- Or increase the load up to 7W or 8W as per your specification.

Then for AC input:
- Place a fuse, a bridge rectifier diode a pi filter to help attenuate EMI noise with a high
capacitance value for input capacitor (1000uF to 4700uF).
- Gradually increase the input to 18Vac at no load, monitor the output.
- Once output of 12V is already regulated gradually increase the load from no load to 7W, 8W
and 10W.

The InnoSwitch3 IC used is INN3977CQ, actually this is for automotive application as we can see the input voltage is very high.
This is just a reference, once the unit is good we can replaced the IC with lower drain voltage.

BOM is already included in the design example including the flyback transformer which is from Payton.
Schematic and layout is also provided.