LMR14030: The noise of inductor

Shaw Wong

Part Number: LMR14030

Hi,

Our customer use LMR14030 to convert 12V to 5V, then convert 5V to 1.25V, at least 200mA as the core voltage of MCU by another DC-DC switching at about 1.2MHz. However, when MCU works, the inductor of LMR14030 has squeaking. If the 5V-1.25V DC-DC is no-load, the noise disappear. So I think the load current can cause noise of inductor, now what method we can do to eliminate this inductor noise?

over 6 years ago

0 Gavin Wang (Zejing) over 6 years ago

TI__Expert 3480 points

Can you share the schematic and PCB layout? And can you measure the waveforms for two inductor current when the inductor has squeaking?

0 Shaw Wong over 6 years ago in reply to Gavin Wang (Zejing)

Intellectual 590 points

Hi Gavin,

The customer design PCB as layout example of datasheet, the schematic, power design block, inductor parameter and the waveform of SW and output voltage as follows. Please help to analyze this problem, thanks.