LM3488: How to set frequency?

tobozocska

Part Number: LM3488

The datasheet says that the LM3488 can operate between 100kHz and 1MHz.

The example circuit uses 40K ohm resistor for RFA and the text mentions 350kHz. I can not find the equation to calculate the resistor value for the desired frequency.

Could you please let me know?

over 7 years ago

0 Garrett Roecker over 7 years ago

TI__Mastermind 21720 points

Hi Tobozocska,

Please reference figure 4 of the datasheet. This will show the relationship between the RFA resistor and the switching frequency.

-Garrett

0 tobozocska over 7 years ago in reply to Garrett Roecker

Prodigy 130 points

If the characteristic have been measured so nicely, is it possible to fit a trend-line to it, just as it have been done for other chips in the same family?

0 Garrett Roecker over 7 years ago in reply to tobozocska

TI__Mastermind 21720 points

Hi Tobozocska,

Please follow the equation.

Rfa = 4.503*(10^11)*(fsw^-1.26)

-Garrett

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LM3488: How to set frequency?