Solution Finder Get Tech Support

Tny 290

Posted by: arunas on

 

                              Hi, 

 

  I have read information I can regulate TNY290 current limit by changing capacitor on the BP pin. Is it possible

    to do it  dynamically ?   ( When  capacitor = 1uF, noises  emission   is much lower to wires and especially  to air  )

 

 

      Arunas

Comments

Submitted by PI-Terry on 09/02/2014

Hi,

The TNY switch detecting the capacitor value on the BP pin during start up only, so it is not possible to do it dynamically. 

Submitted by arunas on 09/02/2014

   thanks PI-Terry,

 

   Is it another solution ?

Submitted by PI-Terry on 09/03/2014

Hi,

Would you please describe your requirement in more detail?

What is the issue of using smaller capacitor value on the BP pin, is the radiation emmission test failed?

Submitted by arunas on 09/03/2014

Power supply requirements:

     1. Uin 50.. 260 VAC

      2. Uout  = 12V,  0.5A

      3. must start  at  300mT   static magnetic field near transformer  and doesn't stop.  

 

      If  mosfet's  drain  current  is  >500mA,  solution pass   last requirement with additionaly power management

         in the secondary  side 

Submitted by PI-Terry on 09/04/2014

 

Hi,

 

Thanks for the information. This is quite usual requirement for the power supply design, that you could use TNY Switc directly.

Do you have any special requirement for current limit dynamically change during operation, which was originally asked from you?  

    I think could be more clear if I say  this solution is for electricity meter. In normaly situation  no need  high immunity  to strong magnetic field , but  sometimes "people"  like steal  energy. So we must protect device and do it  without violation

to another requirement like power conpsumption, EMC , EMI.

Submitted by PI-Sarek on 09/12/2014

Hi,

 

If the Bypass pin capacitor is physically located very close to the IC and also capacitor with extremely small parasitic inductance such as a surface mount capacitor is used, that should reduce likelihood of the problem.

 

Could you please verify the effect of placement of the bypass pin capacitor directly on the IC terminals or very close and also using surface mount capacitor?

 

Regards PI-Sarek