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  • Author Author: tariq.ahmad
  • Date Created: Date Created
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A Noise-Free DIY Switching Power Supply - How Hard Can It Be? -- Episode 542

Switch Mode Power Supplies (SMPS) need a printed circuit board (PCB). To see why check out this video. We look at how hard could it be to get a PCB design right! Hint: You need copper zones to get a low-noise SMPS design.

 

Supplemental Content:

 

Bill of Material:

Product Name Manufacturer Quantity Buy Kit
DC/DC CONV, BUCK/BOOST/INVERT, 85DEG C On-Semi 1 Buy Now
Small Signal Schottky Diode, Single, 45 V, 8 A, 570 mV, 120 A, 150 °C Vishay 1 Buy Now
Power Inductor (SMD), 180 uH, 1.9 A, Shielded, 1.6 A, SRR1210 Series, 12mm x 12mm x 10mm Bourns 1 Buy Now
CAP, 4700uF, 16V, RADIAL, SMD PANASONIC 1 Buy Now
SMD Multilayer Ceramic Capacitor, 0.47 µF, 25 V, 0805 [2012 Metric], ± 10%, X7R, -55 °C SAMSUNG ELECTRO-MECHANICS 1 Buy Now
Surface Mount Thick Film Resistor, CRG Series, 68 kohm, 330 mW, - 5%, 150 V RoHS Compliant: Yes TE CONNECTIVITY 1 Buy Now
SMD Aluminum Electrolytic Capacitor, Radial Can - SMD, 330 µF, 25 V, 0.8 ohm, 2000 hours @ 85°C NIC COMPONENTS 1 Buy Now
 

Additional Parts:

PCBs: Auto-Routed, 6mil no pour, 6mil with ground pour, and Copper Zones

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  • The biggest issue I have with designing switching power supplies is that I am unable to predict performance. Noise performance, thermal performance, efficiency and even current capacity. I need my prototypes to work well on the first spin. Cloning a reference design might be a way to reduce risk, but I usually find it very hard to procure the exact BoM used in the reference design, and the PCB layout is often wasteful of space. It is also common that the reference design doesn't meet all the requirements of the application. Maybe if I invested the time and money in perfecting my own reference designs I could get to a comfortable place, but I'm not there yet.

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  • The biggest issue I have with designing switching power supplies is that I am unable to predict performance. Noise performance, thermal performance, efficiency and even current capacity. I need my prototypes to work well on the first spin. Cloning a reference design might be a way to reduce risk, but I usually find it very hard to procure the exact BoM used in the reference design, and the PCB layout is often wasteful of space. It is also common that the reference design doesn't meet all the requirements of the application. Maybe if I invested the time and money in perfecting my own reference designs I could get to a comfortable place, but I'm not there yet.

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  • in reply to dougw

    I'm with you. Even with good simulation tools, predicting how the passives actually work is a huge challenge.

    Pre-2020 supply shortage, I would stick to a couple of switch controllers.

    Any time I use a new one, I always build a separate power supply module (similar to the boards I did in this video) so I can test them a bit before incorporating them into a final design.

    The upside is you get lots of design practice and a handful of modules. The downside to the shortage situation is that I am not building experience with any particular parts.