• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 336 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Power supply

Utsav Sharma12
Intellectual 420 points

Hello Team TI,

I made a circuit using LM7805 for getting 5V fro 12V. Further I used LD1117 for getting 3.3 V from 5V and then use a resistor divider circuit of 100ohm to get 1.5V. I used electrolytic capacitors across each voltage converter IC. Now when I connect input 12V pins from an adapter of 12V, 2A, output is stable. However, when I connect 12V input from a 12V battery source then I LM7805 heats dangerously high. What would be the possible explanation of this behavior of LM7805?

How different TI voltage regulators are better than LM7805?

  • 0
    TI__Mastermind 49960 points

    HI Utsav,

    5V from 12V is a lot of power dissipation for any linear regulator. this is 14 watts of power at 2A. If it isn't getting as hot when using the adapter, is the adapter really supplying 12V at 2A? I suspect the adapter's voltage may be far less than 12V which might explain what is going on. 

    What package are you using for this? I think your primary consideration should be to select the regulator that has the best TJA. For the LM78 this is the TO-220 package. 

    Also, we have a much more modern version of the 1117, the TLV767 is available.  This has a much lower IQ and has way better inrush control. Another option could be TLV759. 

    I hope this helps.