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Project-LabAnalogDesign2

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The goal of this lab was to design a 5 - 9V to 3,3V (500 mA min) buck converter from the ground up. We had to start from a given chip (RT8259GE) and create the rest ourselves.

Careful layout considerations were taken to lead to an optimal design. The resistor is not on the schematic but only on the board layout. It's footprint was used to jump over the feedback track so everything is on the top layer. A via to GND is placed around it as well for redundancy.

  • JP1 can be used to disable the buck converter.
  • JP2 can be used to bypass the sense resistor R3 (measures the diode current).
  • A lot of test points (TPx) are given to be able to measure different voltages.
  • C4 and C5 are footprints for extra capacitors if the signals have too much ripple.
  • VIN: 4,5 - 24 V
  • VOUT: 3,3 V @ 1,2 A max
  • Click here to go to the schematic.
  • Click here to go to the report (Dutch).

PCB front     PCB back

PCB populated


BOM

Component Value Footprint Other Ordering
U1 RT8259GE SOT-23-6 Richtek
C1, C4 10 µF 1206 (X7R), 50V, 10% Mouser.be
C2, C5 22 µF 1206 X7R, 10V, 10% Mouser.be
C3 10 nF = 0,01 µF 0805 X7R, 50V, 10% Mouser.be
D1 If = 2A Vr = 40V Vf = 0,43V SMA/SMB Mouser.be
L1 4,7 µH NR8040 Taiyo Yuden Mouser.be
R1 62 kΩ 0805 0,5% Mouser.be
R2 19,6 kΩ 0805 0,5% Mouser.be
R3 0,1 Ω = 100 mΩ 1206 1% Mouser.be
0 Ω 1206 Mouser.be
J1, J2 PTSA_1,5/_2-3,5-Z_BK Pitch: 3,5 mm 2 contacts, 250V 2A Mouser.be

WARNING: The pinout of J1 and J2 is reversed due to a footprint error (wrong top/bottom view). The Phoenix Contact connectors can however be manually separated and put back together in a way that they do fit on the board.