Resonant DC-DC converter (TI)

lin,

Can you check that the value of Gui_Vin is between 15-22V?  This value corresponds to the input voltage for the board.

You may also want to quickly confirm that Gui_Vout is set to qvalue(10).

In open loop, the LLC converter's output voltage is dependent on the input voltage, the switching frequency, and the load.  This relationship is shown in Fig-6 of the guide you are looking at.  Therefore, if you have a 15V input and a high load what you are seeing may be expected.


Thank you,
Brett

Brett,

my Gui_Vin is 20-21 V , input voltage (Q10) also in this range. But  Gui_Vout in watch windows display 5-6V

only different between my code with demo code is Period , in my code watch window period[1] is 760

the output voltage :

the output voltage just like DC , in figures I dont know what is it .......

thank you,

lin

lin,

What is your load?


Thanks,
Brett

Brett,

i didnt connect the load.

Should I connect the load? Range?

thx,

lin

lin,

According to the Lab document, a load less than 1.2A is needed.  The Vout sensing should work fine without a load, however in order to see the gain vs frequency curves that are shown you'll need to have some load.

Can you take a look at J7 and J8 on your board and see if a jumper has been placed across the position labeled VfbR?  If there is not one, please try placing one there.  If there are any other jumpers on J7/J8 remove them.


Thanks,
Brett

Brett,

I place the jumper on labeled VfbR, in VOM my output stil zero(about 200mv).

in watch window can see Vout is 6.x V, 

the VhbR to the ground(labeled ground on the board) on scope

Thank you,

lin

lin,

You could try with some small amount of load (maybe something like 1W) and see if things start looking correct.

That being said, this looks like some kind of a hardware issue.  In open loop and even with no load,  the output should be more stable than this.  You may want to talk to customer support in order to try to get a replacement board:
https://estore.ti.com/faq.aspx#q5.1


Thank you,
Brett