Other Parts Discussed in Thread: LMV431
Hi Guys,
Good day! Could you help to check our customer's concern.
Reposting here for the complete details of the inquiry.
The heart of the circuit is a TL431a, it has a reference voltage on the spindle 1 of 2.50V.
My concern is to descend the output voltage below the 3.65V currently available with current values.
Given the concept of the circuit I guess we must not be able to go down below the ref of the TL431?
A voltage min at 3V would suit me, for the max it is not too important if I can get 15V or more it will go.
So I replaced R10 from 39k by a 50K Pot. and R11 4K7 with another 5K pot.
With the original adjustment for R10 and R11 I observe a variation of the value of the output voltage of 3.65V to 24.1V.
If I modify R11 (R10 to Typ.) Only the value of the max voltage changes, with 4K7 I get 23.1V, with 4K it rises to 26.3V, but in the 2 cases the min remains at 3.65V !!!
In the other case, if I fix R11 and modifies R10 this is the value of the max which decreases, the min remaining at 3.65V.
So, my concern is to decrease Vout value under 3V, actually I got 3.65V with RV1 to the Min (R13 connected to R15) With this new configuration (see Regul.jpg) using PNP transistor to load the opto-Led, I reduce by 0.5V but this is to high for me. BTW using a LMV431 instead can reduce my output voltage bellow 3V or can I replace TL431A by a LMV431?
I do not have too much idea about the operation of the circuit. Some explanations could help me.
Looking forward to your response and thank you in advance for the support.
Best regards,
Jonathan
