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I have to do a DC DC conversion from 36V to 32V @1.5A. I found some switching regulators, but no linear regulators. I'm not sure using a switching regulator is the best solution (price, overkill, efficiency) to reduce voltage.

What would you advise?

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  • \$\begingroup\$ Linear will be 88% efficient (32/36) and dissipate 6 watts. Since your 32V load uses 48W it most likely has a heatsink and a fan already, so getting rid of 6 extra watts should be easy. Switching DC-DC could be 90-95% efficiency, saving a few watts... not really worth it... Now, to suggest a regulator is impossible without knowing what the load is, notably its PSRR and regulation needs. \$\endgroup\$ – peufeu Apr 8 '17 at 17:06
  • \$\begingroup\$ DC-DC usually implies some form of input-output isolation - is this what you are looking for? If not call it a regulator. \$\endgroup\$ – Andy aka Apr 8 '17 at 18:03
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    \$\begingroup\$ DC-DC does not imply isolation (Buck is a DC-DC for example). Still, without knowing the load's needs, can't reply... \$\endgroup\$ – peufeu Apr 8 '17 at 18:24
  • \$\begingroup\$ load will be an audio power amplifier. \$\endgroup\$ – rem Apr 8 '17 at 19:15
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Use a standard 3 pin adjustable linear regulator. You can use those at much higher voltages since they do not directly use a ground reference.

Limiting factor is Delta Vin-Vout.

e.g. enter image description here

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    \$\begingroup\$ Upvoting this, since the other answers are... hmmm, LOL... and this is the only one which will work. I'm still waiting for the OP to confess that his load is a motor or something like that, though... \$\endgroup\$ – peufeu Apr 8 '17 at 19:11
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How about an op-amp voltage follower: -

enter image description here

Plenty of op-amps will run above 36 volts so this shouldn't be a problem. I might be tempted to add output current limiting as well if the 36 volt supply is capable of many amps. The NPN transistor need to be a power transistor of course and requires a heatsink for the volt drop (4 volts) x 1.5 amps of max power.

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A simple NPN-zener regulator would do the job. Adjust you zener voltage accordingly. You can stack several zener diodes in series to make 32+~0.7 V in total. Choose a NPN which can handle more than your maximum input voltage plus margin, more than your maximum current and can dissipate (36-32)*1.5 W. enter image description here

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    \$\begingroup\$ NPN not PNP! Also add an op amp for better regulation. \$\endgroup\$ – dirac16 Apr 8 '17 at 17:13
  • \$\begingroup\$ @dirac16 Sorry. I'll edit. \$\endgroup\$ – winny Apr 8 '17 at 18:24

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