STMicroelectronics provides a recommended PCB layout in the application note AN4967, which includes guidelines for thermal pad connection, copper pouring, and via placement to ensure optimal thermal performance.
The thermal shutdown feature is enabled by default. To handle it, monitor the TSD (Thermal Shutdown) pin, which goes low when the device reaches the thermal shutdown temperature (typically 150°C). When TSD is low, the device is disabled, and the output voltage is reduced to prevent overheating.
Although the datasheet specifies a maximum input voltage of 26V, it's recommended to limit the input voltage to 24V to ensure reliable operation and prevent damage to the device.
The output voltage ripple can be calculated using the formula: ΔVout = (Iout * ESL) / (Cout * fsw), where ESL is the equivalent series inductance of the output capacitor, Cout is the output capacitance, and fsw is the switching frequency.
STMicroelectronics recommends using a low-ESR ceramic capacitor (e.g., X7R or X5R) with a value of 10uF to 22uF, depending on the input voltage and operating frequency, to ensure stable operation and minimize input voltage ripple.
SM4T26AY datasheet
by STMicroelectronics
