A good PCB layout for the LM4951ASD/NOPB involves separating the analog and digital grounds, using a star-ground configuration, and placing the device close to the power supply. Additionally, it's recommended to use a 4-layer PCB with a dedicated ground plane to reduce noise and electromagnetic interference (EMI).
The output filter components (Rout and Cout) should be chosen based on the desired output impedance, ripple rejection, and stability requirements. A good starting point is to use the recommended values in the datasheet, and then adjust them based on the specific application requirements. It's also important to consider the ESR (Equivalent Series Resistance) of the output capacitor when selecting the component values.
The LM4951ASD/NOPB has an absolute maximum input voltage rating of 18V. However, the recommended maximum input voltage is 15V to ensure reliable operation and to prevent damage to the device. It's also important to ensure that the input voltage does not exceed the maximum rating during power-up or power-down sequences.
To ensure stability, it's essential to follow the recommended layout and component selection guidelines in the datasheet. Additionally, it's crucial to ensure that the output capacitor has a low ESR and that the output filter components are properly selected. It's also recommended to add a small ceramic capacitor (e.g., 10nF) between the VIN and GND pins to improve stability.
The thermal derating curve for the LM4951ASD/NOPB is provided in the datasheet. The device's performance is affected by temperature, and the output current capability decreases as the temperature increases. It's essential to ensure that the device operates within the recommended temperature range (–40°C to 125°C) and that the thermal design is adequate to prevent overheating.
LM4951ASD/NOPB datasheet
by Texas Instruments
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