TNY284 peak current with LP=484uH

Hi treez,

I recommend you use the PI XLS online tool. You can enter your design parameters and you will be given recommended values for transformer primary inductance, as well as operating parameters such as peak primary switch current.

https://piexpertonline.power.com/

Thanks, but with respect, i dont need a design tool to help me do a 1W flyback. (and it wont tell me the data i need) All i need to know about TNY284 is 1....what is the reference voltage on the current sense comparator, 2....what is the current sense resistor, and 3....what is the current sense delay on the current sense comparator.........these are details which one has available when using most other controllers from other companies. Sorry i am just being honest. TNYswitch is better than all other controllers on the market for this purpose, but i dont understand why you dont give this information. However having said that, the datasheet does give a figure of 150ns......so i presume i can work it back from this. But it seems strange that the datasheet gives the peak current level for 50mA/us....that is just not going to be relevant for most people.....why cant PI just give 1,2,3 above?...I am not directing this at your self...i appreciate your time...i know you will be bounded by the inertia of your organisation.

Ive just used piexpert and it gave me an innoswitch design. The peak current for innoswitch is too high for a 1w flyback...i selected tnyswitch but it for some reason changed it to innoswitch...(and by the way it said "no optimisation")

Hi treez,

TNY ICs do not have a dedicated current sense resistor. The switch current is directly measured from the MOSFET's Rdson.

For applications with di/dt above the datasheet test conditions (50mA/us, page 13), users can use Figure 25 (page 19) to estimate the current limit based on the normalized di/dt.

For your application, it's better to use Figure 21(page 18). An initial calculation of on-time based on VMAX, L, and nominal Ilim(250mA), results in ~300ns. Based on the graph, and because of this very low on-time, the device Ilim will follow I_INIT(page 15). So you can expect Ilim to be 77 to 90% of nominal Ilim, depending on the device temperature.