The UC3843D8G4 is a high-frequency switching regulator, and proper PCB layout is crucial for its operation. TI recommends a 4-layer PCB with a solid ground plane, and to keep the switching node (pins 3 and 4) as short as possible. Also, decouple the IC with a 10nF capacitor between VCC and GND, and use a ferrite bead or a resistor in series with the output capacitor to reduce EMI.
The output voltage of the UC3843D8G4 can be calculated using the formula: Vout = Vref x (1 + R1/R2), where Vref is the internal reference voltage (2.5V), R1 is the resistor connected between the output and the feedback pin, and R2 is the resistor connected between the feedback pin and ground.
The UC3843D8G4 can handle a maximum input voltage of 30V, but it's recommended to keep the input voltage below 28V to ensure reliable operation and to prevent damage to the IC.
The inductor value depends on the output current, switching frequency, and input voltage. A good starting point is to use the formula: L = (Vin x Vout) / (f x ΔI), where Vin is the input voltage, Vout is the output voltage, f is the switching frequency, and ΔI is the desired ripple current. TI also provides an inductor selection guide in the datasheet.
The bootstrap capacitor (Cboot) is used to generate the gate drive voltage for the high-side switch. It's charged through the internal diode (D1) when the low-side switch is on, and discharges when the high-side switch is on, providing the necessary voltage to drive the gate.
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About Texas Instruments
Texas Instruments (TI) designs and manufactures semiconductors and integrated circuits for a wide range of applications. The company's product portfolio includes analog chips, which are essential for managing power and signal functions in electronic devices, and embedded processors, which serve as the brains in various systems, enabling functionality in everything from industrial equipment to consumer electronics. TI's innovations in semiconductor technology have made it a leader in the industry.
