UCC256404: OUTPUT CURRENT CONTROL WITH VARIATION ON VR IR ISENSE PINS

robin gangopadhya18

Part Number: UCC256404

Hello:

Is it possible to control the output load current of the LLC stage by varying either R14 in Figure 3 of the attached Eval kit ug or by varying VR node voltage by a shunted digital potentiometer?

Any help in the matter will be highly appreciated

over 1 year ago

0 Richard Yang1 over 1 year ago

TI__Intellectual 1170 points

Hi Robin:

if changing R14, that means the current limit point is changed, that it does not relate to the control. if you need the constant current control, it shall be with a feedback control change, please help to refer to the design by

www.ti.com/.../PMP40766

So, if it is possible to let us know your final design objective, thanks!

0 robin gangopadhya18 over 1 year ago in reply to Richard Yang1

Mastermind 6156 points

Hello Richard:

Design objectives are

- compact highly efficient GaN based LED driver with DC dimming control- by LED current.

- PFC across line and load- so no triac possible.

-Power output typically 20W to 120W to the LED string.

We have the PFC topology and the remote DC control- looking for the optimum place to apply it. From your reply, we got to look into the secondary side.

Any suggestion on ICs for these functions will be highly appreciated.

0 Manikanta Pallantla over 1 year ago in reply to robin gangopadhya18

TI__Genius 14955 points

Hi Robin,

What's the LLC resonant frequency that you are looking for?

Regards

Manikanta P

0 robin gangopadhya18 over 1 year ago in reply to Manikanta Pallantla

Mastermind 6156 points

Hello Manikanta:

It is not fixed. Given overall system objectives, any suitable frq will do.

thnx for the prompt reply!

very much appreciated

0 Manikanta Pallantla over 1 year ago in reply to robin gangopadhya18

TI__Genius 14955 points

The Ucc25640x is recommended for resonant frequencies only up to 300kHz.

So, for such a frequency range, you don't need to use Gan devices.

That's the reason I was asking about the frequency you are aiming for.

Regards

Manikanta P

0 robin gangopadhya18 over 1 year ago in reply to Manikanta Pallantla

Mastermind 6156 points

GOT IT.

THNX AGAIN.

CLOSING THE POST

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UCC256404: OUTPUT CURRENT CONTROL WITH VARIATION ON VR IR ISENSE PINS