Choosing a Power Supply for Your Project
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Choosing a Power Supply for Your Project
Quick answer: Matching voltage and current on the label isn't always enough — a Raspberry Pi 5 needs its supply to negotiate USB-C PD correctly, not just deliver 5V/5A, or it throttles. A buck converter needs at least 2V of input headroom above its output. And a "700mA" breadboard power module may only sustain about 500mA in practice.
Written and fact-checked by Compoden's engineering team, India. Every spec and known issue below is read from our live catalogue record for the exact part named. Published 19 August 2026 · Last updated 19 August 2026.
Picking a power supply looks like matching two numbers — volts and amps — and most of the time that's genuinely all it takes. The mistakes worth knowing about are the exceptions: a device that needs more than volts and amps to actually work right, a converter that needs headroom the spec sheet doesn't shout about, and a rated current that quietly isn't the real sustained number.
| Part | What the label says | What actually matters |
|---|---|---|
| Official Pi 5 27W USB-C PD Supply | 5.1V / 5A | Must PD-negotiate correctly, not just deliver the current |
| LM2596 Buck Converter | Output adjustable 1.25-37V, up to 3A | Input must be ≥2V above the target output |
| MB102 Breadboard Power Module | Rated 700mA total | Real sustained output often closer to 500mA |
Verdict in one line: the printed voltage and current are necessary but not always sufficient — read the known-issues line on any power part before trusting the headline spec alone.
Why isn't "5V, 5A" always enough for a Raspberry Pi 5?
Because the Pi 5 needs its supply to speak USB-C Power Delivery correctly, not just physically carry that much current. Our own record for the official 27W supply states it plainly: it provides "5.1V/5A to prevent under-voltage throttling," and separately warns that "a generic 5V/5A USB-C PD charger may work but lacks official Pi 5 compatibility and may cause instability." A charger can print 5V/5A on the box and still fail to negotiate the exact PD profile the Pi 5 expects, which shows up as random throttling or instability that looks like a software problem. This is the exception, not the rule — most 5V devices genuinely only need matching volts and enough amps — but a board this power-hungry and this new is worth checking against, rather than assuming any 5A-rated charger will do.
Why does my buck converter refuse to output what I set it to?
Insufficient input headroom, almost always. Our LM2596 record states the requirement directly: "Input must be at least 2V above output." Try to get a clean 5V out of a 5V input, or even a 6V input, and the converter simply can't — it needs roughly 7V or more in to reliably deliver 5V out. This trips people who assume a buck converter can take an input equal to or barely above its target, when the switching regulator inside genuinely needs that margin to work. The fix is either a higher-voltage source or, if the input is fixed and close to the target, a linear regulator instead of a switching buck converter for that specific gap.
Is a module's rated current the number I should actually design around?
Not always — read the known issues, not just the headline spec. Our MB102 breadboard power module is rated 700mA total, but its own record adds an honest caveat: "Maximum current rating is often optimistic; real sustained output may be lower (~500mA total)." That's roughly a 30% gap between the printed number and what the part reliably sustains under real load. Designing a project that draws close to 700mA continuously from this module — several LEDs, a motor, a handful of sensors — risks exactly the kind of intermittent brownout that's hard to diagnose because the multimeter reading at idle looks fine.
How do you pick between a wall adapter, a buck converter, and a breadboard power module?
By where the voltage conversion actually needs to happen. A wall adapter (our catalogue carries fixed options from 5V/2A up through 24V/3A) is the right choice when a project's supply voltage is fixed and known in advance — a 12V relay board, a 5V Raspberry Pi. A buck or boost converter belongs in the middle of a build, when you already have one DC voltage (a 12V battery, a higher-voltage adapter) and need a different one for part of the circuit — our LM2596 for stepping down, or an XL6019/XL6009 for stepping up. A breadboard power module like the MB102 is for prototyping convenience specifically, clipping onto a breadboard's rails to give quick 3.3V/5V without a separate adapter for every test — not for a finished, current-hungry build.
What should you actually buy?
For a Raspberry Pi 5 specifically, the Official 27W USB-C PD Power Supply (Rs.1,260) — worth the premium over a generic PD charger given the instability risk our own record names. For stepping a higher DC voltage down to what a project needs, the LM2596 Buck Converter (Rs.95), remembering the 2V headroom rule. For breadboard prototyping at modest current, the MB102 Breadboard Power Supply Module (Rs.75), designed to well under its 700mA rating rather than up against it. All available cash on delivery across India.
What should you read next?
Powering an ESP32-CAM specifically? Our ESP32-CAM setup guide covers that board's own brownout threshold in detail, and our datasheet-reading guide covers the active-vs-peak current distinction that explains a lot of these supply mismatches generally.
Not sure what your project actually needs to be powered? Open Soldr, describe the parts you're using, and it will work out the supply and any conversion your build needs.
Frequently asked questions
Apne project ke liye sahi power supply kaise chunein?
Voltage aur current match karna zaroori hai, lekin hamesha kaafi nahi hota. Raspberry Pi 5 ko sirf 5V/5A nahi, sahi USB-C PD negotiation bhi chahiye - generic charger instability de sakta hai. Buck converter mein input, target output se kam se kam 2V zyada hona chahiye. Aur kuch modules ki rated current asal mein kam hoti hai - MB102 700mA rated hai lekin asal mein ~500mA tak hi reliable hai.
Why won't my LM2596 buck converter output the voltage I set?
Most likely insufficient input headroom. Our record states the input must be at least 2V above the target output - trying to get 5V out of a 5V or 6V input won't work reliably, since the switching regulator needs that margin. Use a higher-voltage input, or switch to a linear regulator if the gap between input and target is small.
Can I use any 5V/5A USB-C charger for a Raspberry Pi 5?
Not reliably. Our own record for the official Pi 5 supply warns that a generic 5V/5A USB-C PD charger "may work but lacks official Pi 5 compatibility and may cause instability" — the Pi 5 needs correct PD negotiation, not just enough raw current on paper. This is specific to the Pi 5's power demands, not a general rule for every 5V device.
What is the price of a power supply for electronics projects in India?
At Compoden, the Official 27W USB-C PD Power Supply for Raspberry Pi 5 is Rs.1,260, the LM2596 Buck Converter is Rs.95, and the MB102 Breadboard Power Supply Module is Rs.75. All available with cash on delivery across India. Prices checked August 2026.