The recommended input capacitor value is 1uF to 10uF, depending on the input voltage and output current requirements. A larger capacitor value can help reduce input voltage ripple and improve overall system stability.
The output inductor value depends on the output voltage, output current, and switching frequency. A general rule of thumb is to choose an inductor value that results in a peak-to-peak ripple current of 20-30% of the maximum output current. TI provides an inductor selection guide in the datasheet to help with this process.
The bootstrap capacitor (CBOOT) is used to generate the high-side gate drive voltage for the power MOSFET. It is charged through the internal bootstrap diode (DBOOT) and provides the necessary voltage to turn on the high-side MOSFET.
The switching frequency of the UC2845D8 can be adjusted by changing the value of the resistor connected to the RT pin. A smaller resistor value increases the switching frequency, while a larger resistor value decreases it. However, be careful not to exceed the maximum recommended switching frequency to avoid increased losses and EMI.
The maximum output current capability of the UC2845D8 depends on the input voltage, output voltage, and thermal design of the system. The datasheet provides a graph showing the maximum output current vs. input voltage. As a general rule, the UC2845D8 can deliver up to 4A of output current with proper thermal design and heat sinking.
UC2845D8 datasheet
by Texas Instruments
