Goal:

The object of this project was to design a Switched-Mode Power Supply (SMPS).


Design:

Linear Technology’s LT1076 step-down switching regulator was used in the positive buck converter configuration. This design stepped 25V down to 5V at 5mA with a 1000Ω load. The schematic for the SMPS is shown below in Figure 1.

Figure 1: Switched-Mode Power Supply Schematic


Simulation:

The simulation results for the SMPS are shown in Figure 5. The top plot plane with V(n003) and V(n002) shows the 25V input which will be coming from a transformer. V(in) shows the rectified transformer output, which is approximately 25V.

V(out) and I(Rload) show the output across the load which was approximately 5v at 5mA. The current through I(L1) demonstrated that the SMPS was operating in discontinuous mode.

Figure 2: Switched-Mode Power Supply Transient Simulation


References:

http://cds.linear.com/docs/en/datasheet/1074fds.pdf