Constant Current Source Design which can source 20A current

Hi Bivin,

LT3763 can’t handle 100V output. The maximum voltage rating for SENSE+ and SENSE– pins is only 60V.

The only IC to survive 100V output is LTC3779 which can also work as a current source. 

Please check if it meets your requirement.

Hi Fil

If i need to design 14A constant current source which can be tuned from 0A to 14A current at maximum rated voltage input as well as output of 150V, what change should be done to figure in last page of http://cds.linear.com/docs/en/datasheet/3779f_%281%29.pdf   . Constant current regulation is bit unclear in data-sheet,  kindly clarify .  What is the effect of Vfld.  How Ith should be controlled. What about LTC3796 IC to regulate current at 100V with 14A.

Thanks & Regards

Bivin George

Hi Fil

I'm getting error in LTspice while opening LTC3779  file, Screen-shot is attached. Let me know how to fix this error.

Hi, Bivin,

The LTC3779 output current loop is not design for controlled current source used in LED application. It is mainly used as output current limit function. Please check other ICs to meet your requirement.

Hi FormerMember

In LTC3779 data-sheet it is mentioned, " Constant-Current Regulation (IAVGSNSP and IAVGSNSN Pins)The  LTC3779  provides  a  constant-current  regulation loop for either input or output current. A sensing resistor close  to  the  input  or  output  capacitor  will  sense  the  input  or  output  current.  When  the  current  exceeds  the  programmed  current  limit,  the  voltage  on  the  ITH  pin  will  be  pulled  down  to  maintain  the  desired  maximum input or output current. "

Kindly explain the above.

Also Fil mentioned that " The only IC to survive 100V output is LTC3779 which can also work as a current source. "

If LTC3779 can't be used, suggest an IC which can be used as constant current regulator to regulate current of 14A at 100V.

What about LT3796 or LT3756 IC to regulate current at 100V with 14A. Please reply asap.

ltc3779ltc3796 lt3756

Regards

Bivin George

Hi, Bivin,

Basically, if the output current reaches the set output current limit, the output current loop will function and make sure it won't go beyond. Otherwise the voltage loop will function to regulate the output voltage. If you have a voltage source output such as a battery, by setting the regulated output voltage higher than the battery voltage, you can make the converter operating as a constant current source with the current equal to the output current limit. For more detailed spec. related questions, please contact our local FAE for more help.

Regards,

Jeoffrey

Hi FormerMember

Kindly explain " Constant-Current Regulation (IAVGSNSP and IAVGSNSN Pins)The  LTC3779  provides  a  constant-current  regulation loop for either input or output current. A sensing resistor close  to  the  input  or  output  capacitor  will  sense  the  input  or  output  current.  When  the  current  exceeds  the  programmed  current  limit,  the  voltage  on  the  ITH  pin  will  be  pulled  down  to  maintain  the  desired  maximum input or output current. " which is given in data-sheet of LTC3779. As per the discussion with your local FAE, he confirmed that LTC3779 can be used as constant current source (with reference to figure in last page of data-sheet) and mentioned it can be used to deliver constant 10A current at maximum 48V output but he was not sure about how to maintain constant current.

Also Lt-spice file for this part is not working, screen shot of error message is attached in above post.

LT-powercad also don't have this part, kindly update software asap.

If this IC is not the right part kindly update your local FAE and suggest a part to implement requirement given in question.

Regards & Thanks

Bivin George

Hi, Bivin,

Please let me know who is the local FAE you discussed with. I will contact him and work together with him to help you.

Regards,

Jeoffrey

Hi FormerMember 

It is praveen jose and rohit tickoo. Please ask them to suggest the best part asap. 

Regards

Bivin George