LMR64010: Output voltage drops

Hi Gareth,

The IC behavior depends on the output voltage level.

If the output voltage drops to lower than the set demand voltage but higher than the input voltage, the boost will increase duty cycle to regulate the output voltage. Eventually, the inductor current will be clamped to the switch current limit (typical 1.5A in LMR64010). Generally, the IC will trigger thermal shutdown since the inductor current keeps working on the limit threshold.

If the output voltage drops to lower than the input voltage, the working condition is similar to soft short. In such devices without short protection, inductor current keeps rising even when MOSFET is turned off and will be out of control. There is high risk that the device is burned out.

Regards

Mulin

Hi Mulin

could you help check below LMR64101 schematic and any need adjust

Hi Gareth,

The recommended feed-forward zero frequency should be around 8kHz. Thus I recommend C351 to be 150pF.

As you mentioned before, the output voltage may drop to lower than target under heavy load. In this condition, inductor current will reach current limit. The device switch current limit is 1.5A typical. The Isat of the selected inductor is 1.3A. It may be not enough. Inductor with 1.5A or higher Isat is recommended.

Regards

Mulin

Hi Mulin

Changed the inductance to 4.7uH 3.5A/4.0A and modified C351 to be 150pF. =》220pf 100pf are useless