The converter’s efficiency was also a determining factor for choosing diodes. Schottky diode selection was based on the reverse-leakage and forward voltage drop characteristics. The diode’s forward voltage became an issue with a decreasing output voltage drop. For this system though, the output voltage ideally remains constant, therefore eliminating this issue. To further increase efficiency of the system, a Schottky diode could be placed in parallel with the synchronous rectifier. This diode would conduct while the switch is off. This provides a smaller and cheaper method than what a simple circuit requires. PCB Grounding Ground wiring can often limit the performance of the system of components placed onto the printed circuit board. In the designers application where efficiency is vital, proper layout techniques must be understood to leave as little unused power as possible. Learning improved methods helped avoid PCB layout problems as well as improved overall system performance. A layout concept known as “star grounding” was introduced, explained and utilized. Ground is used as a reference for linear circuits and as a return for power systems. Elements such as power amplifiers and switching regulators use ground as a return. The ground could also be used as a shield to prevent electromagnetic noise propagation. As a result of all these various uses the ground serves, the method used in laying out the circuit played an important role in preventing interference across areas of the board. The finite parasitic ground resistance of the path between components carries a voltage drop when the connection carries a current. Due to this voltage drop between components and different areas of the boards, element placement was proven again to be important. Figure 33 below displays a block diagram of the circuit placement. Figure - Common Circuit Placement Because of the voltage drop that is created across the connections, the local ground assumes a voltage other than zero. The voltage drop across the parasitic resistance in the case of a power component such as a switching regulator which is time varying, noise creates and accumulates across the board which affects overall voltage accuracy and desired output voltage. Current and resistance are directly related and since the ground resistance is generally low, large inductively induced currents were easily created. These induced currents accumulated into large loop currents and respectively stimulated noise.
The converter’s efficiency was also a determining factor for choosing diodes. Schottky diode selection was based on the reverse-leakage and forward voltage drop characteristics. The diode’s forward voltage became an issue with a decreasing output voltage drop. For this system though, the output voltage ideally remains constant, therefore eliminating this issue. To further increase efficiency of the system, a Schottky diode could be placed in parallel with the synchronous rectifier. This diode would conduct while the switch is off. This provides a smaller and cheaper method than what a simple circuit requires. PCB Grounding Ground wiring can often limit the performance of the system of components placed onto the printed circuit board. In the designers application where efficiency is vital, proper layout techniques must be understood to leave as little unused power as possible. Learning improved methods helped avoid PCB layout problems as well as improved overall system performance. A layout concept known as “star grounding” was introduced, explained and utilized. Ground is used as a reference for linear circuits and as a return for power systems. Elements such as power amplifiers and switching regulators use ground as a return. The ground could also be used as a shield to prevent electromagnetic noise propagation. As a result of all these various uses the ground serves, the method used in laying out the circuit played an important role in preventing interference across areas of the board. The finite parasitic ground resistance of the path between components carries a voltage drop when the connection carries a current. Due to this voltage drop between components and different areas of the boards, element placement was proven again to be important. Figure 33 below displays a block diagram of the circuit placement. Figure - Common Circuit Placement Because of the voltage drop that is created across the connections, the local ground assumes a voltage other than zero. The voltage drop across the parasitic resistance in the case of a power component such as a switching regulator which is time varying, noise creates and accumulates across the board which affects overall voltage accuracy and desired output voltage. Current and resistance are directly related and since the ground resistance is generally low, large inductively induced currents were easily created. These induced currents accumulated into large loop currents and respectively stimulated noise.
Final_Documentation_4915.docx