Tny 290
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
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?
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
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.
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
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.