ROHM recommends a thermal pad on the bottom of the package, connected to a large copper area on the PCB to dissipate heat efficiently. A minimum of 2oz copper thickness is recommended, and the thermal pad should be connected to a ground plane or a dedicated heat sink.
To ensure stable operation with a high-ESR output capacitor, ROHM recommends adding a 1-10nF ceramic capacitor in parallel with the output capacitor to reduce the overall ESR. Additionally, the output capacitor should be placed close to the IC to minimize parasitic inductance.
The maximum allowed voltage on the EN pin is 6V, which is higher than the recommended operating voltage of 5V. However, it's essential to ensure that the EN pin voltage does not exceed the IC's supply voltage (VIN) to prevent damage.
While the BD4947G-TR is rated for operation up to 125°C, ROHM recommends derating the output current and power dissipation to ensure reliable operation in high-temperature environments. Consult ROHM's application notes for specific guidance on thermal derating.
To troubleshoot oscillations or instability issues, check the PCB layout for parasitic inductance and capacitance, ensure proper decoupling of the input and output capacitors, and verify that the output capacitor meets the recommended specifications. Additionally, check for voltage drops on the input and output lines and ensure that the IC is operated within its recommended operating conditions.
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