Viper 22A SMPS AC input range

[jibin@elmeasure.com]

Viper 22A SMPS AC input range 20-300 AC input 50HZ SMPS design

Anybody can help regarding Viper 22A SMPS...Is Viper 22A based supply will support 20-300V AC input supply????

 

[ea.arun]

it will sure support 300V AC..but regarding the 20VAC lower voltage the primary inductance values to be achieved might be too low based on the power requirement at the output(also very low duty cycle).....

EA

 

[FvM]

it will sure support 300V AC

300 VAC will violate the Vds(st) specification without special prequirements.

Presumed the switcher is able to handle extreme high duty cycles (which can't be reliably derived from the datasheet, I think) you shouldn't expect high output power at low input voltage.

 

[jibin@elmeasure.com]

Actually required output is 5v 1A & 3.6V, aux input 20-300VAC...Viper VDD voltage is varying as per the input supply changes .Why it is behaving like that...VDD should not vary according with input supply it vary accordingly with load....can you help me for solving the above mentioned problem..

 

[pradeep.g.belchada]

viper ic is not desgined to handle 20 to 300vac

 

[jibin@elmeasure.com]

viper ic is not desgined to handle 20 to 300vac

I am a beginner so would you please explain why it will not work in that range. Is it possible in the range of 40-300V AC.Please do the needful for my doubts

1.Would you please give the SMPS design tips & calculations
2.Can you give the reference design.

Thanking you

 

[pradeep.g.belchada]

you can desgin it only for 180vac 280vac for satisfactory operation.
in no way any such pwm controller will operate in 40vac

 

[jibin@elmeasure.com]

you can desgin it only for 180vac 280vac for satisfactory operation.
in no way any such pwm controller will operate in 40vac

Here this Viper 22A is working with 40 V AC buy that time i cant use 300V AC that time maximum of voltage range is 40-240,after this range the device will go to over voltage protection. So i want to maintain the VDD voltage under the over voltage condition of viper22(38V) how it will achieve in design.can you give some tips on that.

 

[jibin@elmeasure.com]

Here this Viper 22A is working with 40 V AC but that time i cant use 300V AC that time maximum of voltage range is 40-240,after this range the device will go to over voltage protection. So i want to maintain the VDD voltage under the over voltage condition of viper22(38V) how it will achieve in design.can you give some tips on that.

Dear All,

Any one can help me regarding the D max of viper22A . Is it 0.41 ?


Regards,
Jibin Micheal

 

[phobos1]

h**p://www.te.com/japan/corp/press/pdf/Media_digest12_Flyback_Transformers_e.pdf i am working with viper22a hope we shall share some info. good luck

 

[emontllo]

The Viper 22A will not turn on until VDS > 100 V. With VDS < 100 V it will not charge Vdd capacitor. Figure 10 https://www.st.com/web/en/resource/technical/document/datasheet/CD00087939.pdf
You may be able to operate at 40 VAC if you start-up at 100 V and then you decrease.

Regarding Vdd varying voltage there should be some design problem... Are you using the transformer auxiliary winding for Vdd supply? With which turns ratio? Wich diode are you using in D3 and C5 of Figure 4? https://www.st.com/web/en/resource/technical/document/datasheet/CD00087939.pdf

I would suggest using the eDesignSuite in he ST website to design the circuit components according to your needs.

 

[jibin@elmeasure.com]

The Viper 22A will not turn on until VDS > 100 V. With VDS < 100 V it will not charge Vdd capacitor. Figure 10 https://www.st.com/web/en/resource/technical/document/datasheet/CD00087939.pdf
You may be able to operate at 40 VAC if you start-up at 100 V and then you decrease.

Regarding Vdd varying voltage there should be some design problem... Are you using the transformer auxiliary winding for Vdd supply? With which turns ratio? Wich diode are you using in D3 and C5 of Figure 4? https://www.st.com/web/en/resource/technical/document/datasheet/CD00087939.pdf

I would suggest using the eDesignSuite in he ST website to design the circuit components according to your needs.

Hi Sir,

I am using auxilary winding for VDD supply. winding ration is 4 and D3 & C5 are US1J and 1µF/63V respectively. In data sheet VDS start up voltage has mentioned as -0.3-400 so it should work at 40V AC range.Viper 22A SMPS which i designed it is working at 40VAC but when i connect load more than 0.5 watt the working range has expanded to 65V AC.Can you help me to solving this problem.My expected result is 3W power 40-300VAC working range.


Regards,
Jibin Micheal

 

[mtwieg]

The Viper 22A will not turn on until VDS > 100 V. With VDS < 100 V it will not charge Vdd capacitor. Figure 10 https://www.st.com/web/en/resource/technical/document/datasheet/CD00087939.pdf
You may be able to operate at 40 VAC if you start-up at 100 V and then you decrease.

I don't see anything in the datasheet that defines a clear value for the minimum Vdrain required for startup. That figure just states that the test condition is with 100V<Vdrain<400V. Operation with Vdrain<100V isn't specified, apparently.

In data sheet VDS start up voltage has mentioned as -0.3-400 so it should work at 40V AC range.

That's the absolute max range of Vds, not the operating range...

 

[jibin@elmeasure.com]

I don't see anything in the datasheet that defines a clear value for the minimum Vdrain required for startup. That figure just states that the test condition is with 100V<Vdrain<400V. Operation with Vdrain<100V isn't specified, apparently.

That's the absolute max range of Vds, not the operating range...

Hi,

If VDS minimum start up is 100V means minimum AC voltage at least 70V is it ?

 

[mtwieg]

Again, the datasheet doesn't clearly say what happens under 100V, it might still work but maybe the startup current is decreased or something. If it turns out it doesn't start up with Vds<100V, then you'll either have to use an external startup circuit or another controller.

 

[jibin@elmeasure.com]

Again, the datasheet doesn't clearly say what happens under 100V, it might still work but maybe the startup current is decreased or something. If it turns out it doesn't start up with Vds<100V, then you'll either have to use an external startup circuit or another controller.

Ok..will try with another MOSFET

 

[emontllo]

If it turns out it doesn't start up with Vds<100V, then you'll either have to use an external startup circuit or another controller.

I agree, it is not clearly explained in the datasheet. My experience is with VIPER27 and VIPER17. I have implemented power supplies with those ICs and they do not turn on until Vdrain reaches 60 V ... 100 V according to the datasheet. I tried to design an external power-up circuit (see https://www.edaboard.com/threads/297047/) wich provided a stable VDD voltage and even though the flyback did not turn on until Vdrain reached appropriate voltage mentioned. Having a close look to the datasheet, Viper22 does not include this parameter, therefore it may turn on at lower voltages.

- - - Updated - - -

Jibin: It is normal that VDD is not perfectly constant. When you apply load to the output, the secondary windings and diodes have an additional voltage drop (due to higher current) that does not happen on the auxiliary output. The control loop increases the duty to compensate this extra voltage drop, this means the auxiliary winding voltage increases. Just ensure that Vdd supply range does not exceed the maximum VIPER22 ratings, if so, the auxiliary winding should have lower turn ratio.

Regarding the circuit design I recommend the ST eDesignSuite. Having a quick look at it, I have noticed that below 60 VAC, this online tool cannot find an appropriate AC/DC power supply solution...