UC3825: Switching frequency

Michiaki Tanii

Expert 4460 points

Part Number: UC3825

Hi team,

Could you provide the equation for frequency configuration with RT, CT ?

And are there any application report to know more detail to design circuit with UC3825 ?

Thank you and best regards,

Michiaki

over 4 years ago

0 Teng Feng over 4 years ago

TI__Genius 13660 points

Hi Michiaki,

I didn't find a equation for the frequency of UC3825, you can design the frequency according the figure of "Timing Resistance vs Frequency " in page 6 of datasheet. It is more accurate than the equation.

I only found one UC3825 application note for your reference, http://www.ti.com/lit/an/slua053/slua053.pdf but I think it is more like a power note.

If you want to verify the calculation and design, it is a good solution to use a simulation module which is available online.

https://www.ti.com/product/UC3825/toolssoftware

Regards,

Teng

0 Michiaki Tanii over 4 years ago in reply to Teng Feng

TI__Expert 4460 points

Hi Teng,

Does customer need cut and try on TINA and design without equation ?

Thank you and best regards,

Michiaki

0 Teng Feng over 4 years ago in reply to Michiaki Tanii

TI__Genius 13660 points

Hi Michiaki,

Yes, customer can select the RT and CT according the figure of "Timing Resistance vs Frequency " in page 6 of datasheet. And I recommend to use a simulation to rectify the result if they want.

Regards,

Teng

0 Michiaki Tanii over 4 years ago in reply to Teng Feng

TI__Expert 4460 points

Hi Teng,

Could you kindly advise what difference is between UC3825 and UC3825A/B ?

We can find the more detail in the datasheet of UC3825A/B.

Should we recommend UC3825A/B instead of UC3825?

Thank you and best regards,

Michiaki

0 Teng Feng over 4 years ago in reply to Michiaki Tanii

TI__Genius 13660 points

Hi Michiaki,

In most applications, the UC3825A/B devices are enhanced drop-in replacements for UC3825a/B high speed PWMs. We can recommend UC3825A/B to customer instead of UC3825.

The differences can be easily found in the attached document. And also datasheet.

http://www.ti.com/lit/an/slua125/slua125.pdf

Regards,

Teng

Power management

Power management forum

UC3825: Switching frequency