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A high current power supply built around a server voltage regulator

A high current power supply built around a server voltage regulator

Bill of Materials

Here’s a complete bill of materials for this project. Where a component is available from Farnell I’ve included the order code.

Designator Value Quantity Footprint Description Farnell Order Code Notes
C1, C2, C6, C7, C8, C9, C11, C13, C14 100n 9 2.54mm lead spacing Ceramic capacitor 2309020
C3 22u 16v 1 2mm lead spacing Polarized Capacitor (Radial) 1870976
C4 220u 1 2.5mm lead spacing Polarized Capacitor (Radial) 1902883
C5 220u 1 2.5mm lead spacing Polarized Capacitor (Radial) 1902883
C10 10u 1 2mm lead spacing Polarized Capacitor (Radial) 1902913
C12 1u 1 5.08mm lead spacing Capacitor 2112910 1
D1, D7 1N4007 2 DO-41 1 Amp General Purpose Rectifier 2317417 2
D2 1 LED-3MM 3mm LED 3
D3 1 LED-3MM 3mm LED 3
D4 1 LED-3MM 3mm LED 3
D5 1 LED-3MM 3mm LED 3
D6 SR150 1 DO-204AL Schottky Rectifier 1861420
FB1 BLM18PG221SN1D 1 AXIAL-0.3 Inductor 2292304
K1 OJE-SS-112HMF,F000 1 Relay TE OJ/OJE Single-Pole Single-Throw Relay 1891668
L1 RLB0914-331KL 1 RADIAL 5x9x9.5 Inductor 2309243
L2 RLB0712-100KL 1 RADIAL 10×7.2×3 Inductor 2434811
P1 Edge connector 1 2×25 2.54mm pitch, 5.08mm row spacing 4
P2 PM5.08/2/90 1 PCB terminal block – 2 pin WEIDMULLER PM5.08/2/90 1131855 5
P3 PM5.08/2/90 1 PCB terminal block – 2 pin WEIDMULLER PM5.08/2/90 1131855 5
P4 PM5.08/2/90 2 PCB terminal block – 2×2 pin WEIDMULLER PM5.08/2/90 1131855 5
P5 Fan header 1 HDR1X3 Header, 3-Pin 588581
P6 1 2.54mm Header, 4-Pin 6
P7 1 2.54mm x 2 Header, 5-Pin, Dual row 6
Q1, Q2, Q3, Q4 BS170 4 TO-92 N-Channel MOSFET 1017687
R1, R9 680 2 AXIAL-0.3 Resistor 2329545
R2, R3 470 2 AXIAL-0.3 Resistor 2329531
R4, R7, R10, R12, R13, R14 10k 6 AXIAL-0.3 Resistor 2329474
R5, R6 2.2k 2 AXIAL-0.3 Resistor 2329584
R8 2m 1% 1 2512 Welwyn ULR2-R002FT2 1292491
R11 68k 1 AXIAL-0.3 Resistor 2329546
SW1 PM5.08/2/90 3 PCB terminal block – 3×2 pin WEIDMULLER PM5.08/2/90 1131855 5
SW2 1 PCB terminal block (3 pin) Header, 3-Pin 7
U1 LM2574N-5.0/NOPB 1 DIP-8 0.5A Step-Down Voltage Regulator 1469169 8
U2 INA226AIDGST 1 MSOP-10 Current Sense Amplifier 1924807
U3 MCP9700-E/TO 1 HDR1X3 MCP9700 plus fan-style header 1332166,588581 9
U4 MAX7221CNG 1 DIP-24 8-Digit LED Display Driver 10,8
U5, U7 03641A 2 0.36″ 12 pin 4 digit 7 segment LED common cathode 410561X 11
U6 ATmega328P-PU 1 DIP-28 8-bit AVR Microcontroller 1715487 12,8



Some of the components have note numbers against them. The following numbered paragraphs correspond to a numbered note in the bill of materials table.

  1. 2.54mm parts can also be used if you carefully bend the leads outwards to fit the wider 5.08mm pitch.
  2. Any of the 1N400x series will be fine. They all cost about the same so I tend to keep a stock of the biggest one, the 1N4007 around.
  3. Any colour of 3mm LED will work. I’ve used amber for Power/PGOOD, white for EN and blue for VSP for no other reason than I felt like it.
  4. This can be a tricky one. I got the edge connector on ebay, item number 140888533934. Part 2668415 at Farnell looks like it could be persuaded to fit – the row pitch is only 0.2mm off the required 5.08mm.
  5. PCB terminal blocks with the 5.08mm pitch are plentiful on ebay and they slot together to form longer blocks. There’s no reason not to use the cheaper ebay blocks for the switchgear but I would stick to a quality item for the power in/out blocks (P2, P3 and P4).
  6. The male 2.54mm pin headers are at their cheapest on ebay.
  7. The 3-way 5.08mm PCB terminal blocks are available on ebay.
  8. I mount all my ICs in sockets. You don’t have to but if you need to replace one…
  9. I’ve included a 3×2.54mm header footprint for the TO-92 temperature sensor and I chose to use a 3-pin fan header as the connector. You could just as easily use male and female pin headers if you have them, or even solder the sensor wires directly to the board as the most economical method.
  10. The MAX7221CNG is available cheaply on ebay in lots of 5. As usual with ebay there’s a good chance of them being clones but that’s where I bought mine from and they seem to work.
  11. The 7-segment 0.36″ LED display is available from many ebay sources. Make sure it’s a common cathode configuration. These displays all seem to share a common pinout, but just in case click here to see the datasheet for the one that I bought.
  12. You can probably buy an Arduino clone on ebay from China with an Atmega328P on board for less than Farnell will charge you for one piece of the IC alone.