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I am using (lm2576) 5.0v regulator from 12v battery 2-amps for my raspberry pi. I want to use 3 LDR and 5 proximity IR sensor for my mini project. For all sensor I need only 3.3V voltage. It is sufficient to use 3.3V voltage divider circuit from lm2576-5.0 v reg or else I have to use 3.3 voltage regulator so that I can convert 5v(lm2576) to 3.3v(lm1117/lm3940)

I got 3.3v reg-lm3940 I connected through lm2576 but both regulator getting heat too much and inductor got fire

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  • \$\begingroup\$ Have you tried using LM7805(5v regulator) & LD33V(3.3v regulator)? \$\endgroup\$ – Aircraft Sep 28 '15 at 9:06
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    \$\begingroup\$ No you can't use a divider. Don't use linear regulators for 800ma. Get a couple of small switchmode boards and use those. \$\endgroup\$ – pjc50 Sep 28 '15 at 9:10
  • \$\begingroup\$ Are you using any heatsinks? \$\endgroup\$ – Fizz Sep 28 '15 at 9:14
  • \$\begingroup\$ No,i m not using lm7805 i need 2 amps as output load for that i m using lm2576. \$\endgroup\$ – sarfaraaz Sep 28 '15 at 10:27
  • \$\begingroup\$ yes i m using heatsink \$\endgroup\$ – sarfaraaz Sep 28 '15 at 10:27
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It sounds like you are wasting a lot of energy converting from 12V down to 3.3V, and this is the reason for the overheating. A well designed circuit would waste very little power. Have you looked into using an integrated 12V to 3.3V dc-dc converter ?

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  • \$\begingroup\$ ho if it is that reason then can i use ld33/tl2575-33 \$\endgroup\$ – sarfaraaz Sep 28 '15 at 10:30
  • \$\begingroup\$ You can use these devices but they also require considerable external components. The benefit of the DC-DC converter is that it is all one device (nothing to get wrong, if you are not an electronics specialist) \$\endgroup\$ – jrrk Sep 30 '15 at 17:07
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Use a buck converter, it does not waste so much energy (at least 90% efficiency) like a linear device will do. For example: TL2575-33 (1-A Simple Step-Down Switching Voltage Regulators)

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