2 Prelab
Familiarize yourself with the schematic of the flyback test board before starting the lab. At this point you are not expected to understand the control circuity, which we will be working through over the course of the class. However the flyback converter topology should be familiar from EE153/253. Understanding the switching states and conversion ratio of the flyback converter is important for this lab.
The below table of power stage components used in the flyback converter and their datasheets may be useful in your review of the schematic and in answering the prelab questions.
| Component | Part Number | Datasheet |
|---|---|---|
| Power MOSFET | IRFR120N | |
| Output Diode | B340AE-13 | |
| Flyback Transformer | HR051142 | |
| Controller IC | UC3843B |
2.1 Prelab Questions
- Reviewing datasheets:
- What is the turns ratio of the flyback transformer?
- What is the nominal on resistance of the power MOSFET?
- What is the nominal voltage drop of the output diode?
- Converter Operation:
- For a 12V input and the nominal 5V output what will the duty cycle of the flyback converter be if it is operating in continuous conduction mode (CCM)?
- For a 36V input and the nominal 5V output?