- Thigh D T 2 Design Specifications Table 1 Ensure An Instructor Has Assigned Your Team A Project From Project Fsw K 1 (90.17 KiB) Viewed 63 times
- Thigh D T 2 Design Specifications Table 1 Ensure An Instructor Has Assigned Your Team A Project From Project Fsw K 2 (163.08 KiB) Viewed 63 times
thigh D = T - 2. Design Specifications Table-1. Ensure an instructor has assigned your team a project from Project fsw kHz AVOut A 100 200mV B 100 200m V с 100 200m V Vin Vout Tout AIL 15V 6V 250mA 20% 15V 7V 250mA 30% 15V 8V 250mA 20% 12V 250mA 20% 5V 12V 6V 250mA 30% 12V 7V 250mA 20% 1: Project Specifications D 200 200mV E 200 200mV 200mV F 200 Ta 3. Calculate the duty cycle and component values needed for the circuit in Figure 1 to satisfy assigned project specifications, Vout + VL . RL Vin CF Vd Schottky Square + Figure 1 – Buck Converter Schematic
Calculate Vpulse's Duty Cycle D: Vout = Vin(1 – D) - VD Calculate Inductance L: L= Vp + Vout thigh Δί, Where, the magnitude of the inductor current ripple Aių, as a rule of thumb, should be set to 20% to 40% of the average load current IL [1]. The magnitude of the inductor ripple current is inversely proportional to the size of the inductor. Reference [1] contains more information about the trade-offs encountered when selecting inductor sizes which yield a ripple current closer to 20% vs a ripple current closer to 40%. Calculate Output Capacitor CF: Each cycle, when the inductor current exceeds the output current, the output capacitor voltage increases. When the inductor current is less than the output current, the output capacitor voltage decreases. To achieve the correct average output current and a constant DC output voltage, the amount of the output capacitor charging must be equal to the amount of output capacitor discharging. When selecting an output capacitor, it is important that the ESR be low as to avoid additional ripple; aluminum electrolytics are commonly used. The minimum output capacitance depending on the output capacitive ripple voltage, can be determine by [4] CE Δί, 8(VRipple) T Calculate Input Capacitor C: The buck's input current is discontinuous, turning on when the transistor is on and the diode is off, and off when the transistor is off and the diode is on. Since the input voltage source (battery, AC/DC adapter, etc.) is typically unable to support the required rapid current changes[4], it is the input capacitor's job to supply the charge for the sudden increase in demand for current. Iload C T 4(Vripple) = 4. Build the circuit below in PSPICE using your calculated values and run a transient simulation. Ensure your simulation time is long enough for the filter capacitor "CF" to charge up to the expected value of Vout.