The UCC3809P-2 is a high-frequency device, and proper layout and placement are crucial for its operation. TI recommends placing the device close to the power stage, using short and wide traces for the power lines, and separating the high-current and low-current paths. A good layout practice is to use a star-ground configuration and to minimize the loop area of the power stage.
The value of the VCC bypass capacitor depends on the specific application and the noise sensitivity of the system. A general rule of thumb is to use a capacitor with a value between 10nF to 100nF, with a voltage rating that exceeds the maximum VCC voltage. TI recommends using a low-ESR capacitor with a high self-resonant frequency to ensure effective noise filtering.
The maximum allowable voltage on the VREF pin is 5.5V, which is the absolute maximum rating. However, for normal operation, TI recommends keeping the VREF voltage between 4.5V and 5.5V to ensure accurate voltage regulation.
The output voltage of the UCC3809P-2 can be adjusted by changing the value of the resistors in the voltage divider network connected to the VREF pin. The output voltage is determined by the ratio of the resistors and the internal reference voltage. TI provides a formula in the datasheet to calculate the output voltage based on the resistor values.
The soft-start pin (SS) is used to control the startup sequence of the UCC3809P-2. By connecting a capacitor to the SS pin, the output voltage can be ramped up slowly during startup, reducing the inrush current and preventing voltage overshoots. The value of the capacitor determines the soft-start time, and TI recommends a value between 10nF to 100nF.
UCC3809P-2 datasheet
by Texas Instruments
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