LM5575: RT resistor connection

HI Stani:

we may need to do the lab test to make sure what will happen of RT short or Open and feedback to you

Normally, it will working with highest frequency , lowest frequency or no output.

Thanks

Hello Daniel,

thanks a lot for your quick reply.

I was wondering, is it like that if R is shorted than Buck Regulator will work with highest frequency and open then with lowest frequency?

HI

test on evm with 12V input , no load:

short RT , no output,

Open RT , no output.

and if you test RT by scope, which means add a large impedance from RT to GND,  the device can work at 5V no load condition. 

Thanks

Hello Daniel,

thanks a lot for your useful answers.

In our design we chose 11kOhm resistor and we get 485kHz switching frequency according to equation given in datasheet. And max 500kHz frequency we get by using R=10.5kOhm.

Now my question is: what if in any case resistance will decrease over lifetime, as an example from 11kOhm to 10kOhm resistor then what frequency will be set? Highest frequency 500kHz or Buck will give no output?