L7987 switching frequency

[PZha.1]

HI Sir,

how do we define the switching frequency of the L7987

the switching frequency range is between 250KHz and 1.5MHz

looks like if the switching frequency is set to 1.5MHz, the ripple appears to be much smaller, 

so can we set it to 1.5MHz under normal design.

thanks,

With best regards,

PZha

[AScha.3]

Hi,

see ds :

setting Rfsw to 10k should give about 1.5M.

here R8 :

[PZha.1]

HI Sir,

thanks for your reply, 

could you please advise is there any difference if the switching frequency is set to 10K 1.5MHz and NC 250KHz

thanks, with best regards, PZha

[AScha.3 · Accepted solution]

Hi,

>is there any difference if the switching frequency is set to 10K 1.5MHz and NC 250KHz

hmm... the switching frequency is about (with 10K )  1.5MHz and NC is  250KHz .

Your circuit (the coil L1 , C5+6) has to match the frequency you want/set .

What else ...?

[PZha.1]

HI Sir,

thanks for your support.

with best regards, PZha