A 2-layer or 4-layer PCB with a solid ground plane and thermal vias under the device can help to dissipate heat efficiently. It's also recommended to keep the thermal path short and direct to the heat sink or thermal pad.
To ensure a stable output voltage, make sure to use a suitable output capacitor with a low ESR, and ensure the input voltage is within the recommended range. Also, avoid overloading the device and ensure proper thermal management.
Although the datasheet specifies a maximum input voltage of 42V, it's recommended to derate the input voltage to 36V or lower to ensure reliable operation and to prevent damage to the device.
While the device is rated for operation up to 125°C, it's essential to consider the thermal derating curve and ensure the device is properly cooled to prevent overheating. A heat sink or thermal pad may be necessary to maintain a safe operating temperature.
Use an oscilloscope to monitor the input and output voltages, and check for any signs of oscillation or noise. Also, verify that the device is properly soldered and that the PCB layout is correct. If issues persist, consult the datasheet and application notes for troubleshooting guidance.
LMZ23605TZE/NOPB datasheet
by Texas Instruments
