Texas Instruments recommends a compact layout with the controller, power FETs, and output capacitors placed close together. The input and output stages should be separated to minimize noise coupling. A solid ground plane and a low-impedance power path are also essential for minimizing EMI and noise.
The output inductor should be chosen based on the desired output voltage, output current, and switching frequency. A general rule of thumb is to choose an inductor with a value between 1-10 μH, and a current rating that is at least 1.5 times the maximum output current. The inductor's physical size, core material, and DC resistance should also be considered.
The UC3852DTR has a maximum junction temperature rating of 150°C. However, it's recommended to keep the junction temperature below 125°C to ensure reliable operation and to prevent thermal shutdown.
Yes, the UC3852DTR can be used in designs with high-input voltages, but it requires additional components to regulate the input voltage and prevent overvoltage stress on the controller. A voltage regulator or a resistive divider network can be used to regulate the input voltage to the recommended range of 8-18V.
Oscillations or instability issues can be caused by a variety of factors, including poor layout, inadequate decoupling, or incorrect component values. To troubleshoot, start by checking the layout and ensuring that the input and output stages are properly separated. Verify that the decoupling capacitors are properly placed and sized. Also, check the component values and ensure that they are within the recommended ranges. If the issue persists, consider using a scope to measure the output voltage and current waveforms to identify the source of the oscillation.
UC3852DTR datasheet
by Texas Instruments
