Tool/software:
Hi TI Team,
We are currently using the LM3429MH/NOPB LED driver in a design with the following configuration:
-
Input Voltage: 12V (up to 8A available)
-
LED Configuration: 20 LEDs in series (each with Vf ≈ 3.0V)
-
LED Current: 200 mA
-
Estimated Output Voltage: ~60V
-
Switching MOSFET: 100V Vds, 5A Id rated
-
Output Diode: Properly selected for voltage and current ratings
-
Compensation Network: Tuned according to TI guidelines
We are observing significant power loss, with efficiency dropping below 50%, and the system is experiencing major thermal dissipation issues. The board heats up considerably even with good passive selection and proper layout. We've confirmed that our LC filter, OVP, UVP, and other standard protections are implemented as per the datasheet recommendations.
Despite optimizing the compensation network and component selection (including inductor and sense resistor), the problem persists. Increasing the LED current beyond 200–250 mA with output voltage hovering around 58V leads to excessive heat buildup, damaging passive components in some cases and even triggering thermal shutdown in the LM3429.
We would appreciate your support in identifying potential causes for this inefficiency and guidance on resolving this thermal issue. Is this behavior expected in such a setup, or is there any critical design consideration we might be missing?
Looking forward to your insights.
