LD1086DT50TR

[Udhay]

Hi,

We designed a 24V to 5V DC-DC power supply using the LD1086DT50TR. However, we are experiencing an overheating issue. Our application load current is only 0.2–0.3 A, but the regulator temperature rises significantly. Could you please suggest a solution to resolve this overheating issue?

[mƎALLEm]

Hello and welcome to the ST community,

The overheating issue occurs because LD1086DTxx is a linear low-dropout (LDO) regulator, which sheds excess voltage by converting it entirely into heat. Even at a low current of 0.3A, the (hudge) 19 V drop from 24 V to 5V forces the package to dissipate excessive power.

Power Dissipation:

Pd=(Vin - Vout) x IOUT → Pd=(24V - 5V) x 0.3A = 5.7W that you need to dissipate from a “small” package (DPAK).

Solutions, either to:

• Add a heat sink that dissipates this power surplus of 5.7W. The package is DPAK, need to prepare a copper surface in the PCB to dissipate that power. I doubt that’s possible. Or use TO-220 package and find the right heat sink. You need to find the suitable one by calculation.
• Two-stage regulation: use an intermediate regulator to drop the input voltage from 24V down to 8V-10V, then a second stage: feed that intermediate voltage into your LD1086.
• Or need to find another solution like opting to buck DC-DC converter.

Hope that helps.