For this week’s EYE ON NPI (video), the buck stops here – with the very nice AP6330x series of synchronous buck converters from Diodes Inc.
Diodes Inc isn’t a super flashy company, and yes they do sell a lot of diodes, but they also have rock solid power chips at great prices. Our favorite LDO is the AP2112-3.3K, an ‘every day’ SOT-23-5 LDO but with excellent current capability of 500mA+ and very low drop-out of 0.4V. We use it on just about all our breakouts and dev boards, and we’ve never seen a failure.
But back to this one – the AP63300/AP63301 can easily become your go-to buck converter. It’s got that vibe we get from Diodes chips where we can just tell this is going to be a part we use on a lot of boards, any time we need to down convert. Why? Because it’s got 6 great things going for it:
1) A Wiiiiiiiiide input range – a massive 3.8V to 32VDC (35V absolute max). This converter will take anything you throw at it: DC wall adapters, USB ports, lead-acid batteries, etc.
2) A Wiiiiiiiiide output range too! Anything from 0.8V to 31VDC, just set up the feedback resistor divider
3) Internal FETs and FET booster – minimal external components. You only need in/out bulk capacitors, feedback divider, big inductor and stability capacitors.
4) 3A continuous output current – lots of current for your projects with WiFi or lots of LEDs, it could even be used for some ‘low-current’ robotics projects
5) Package – Ultra-easy to use SOT23-6 is a pleasure to use, not too big but also won’t require any rework when fabricated
6) Price! Only 40 cents per when you buy a reel.
All together, there’s no reason to use an LDO anymore – throw away your ‘1117’s and 780x’s! For about the same price and footprint, you can get a wonderfully efficient buck converter and best of all, no heat sink! We’re definitely going to use this chip as our every-day no-frills buck, just like we use the AP2112 for our every-day LDO.
When you are ready to purchase, note there are two versions – the AP63300 and AP63301. That’s due to two different ways of handling light load conditions, which affects many operational variables. The AP63300 has a PFM/PWM frequency of about 500KHz with some EMI-reducing spread spectrum of about 6% variability, and at low currents it drops from PWM to lower-frequency PFM mode. This gives it a low quiescent current of 22uA, with good efficiencies at low (less than 50mA) currents. However, at low currents, there will be significantly more noise/ripple in the output voltage.
The AP63301 is a PWM-only converter, without the frequency modulation, so it stays at the same 500KHz no matter the load. You get plummeting efficiencies at low current, and higher quiescent current – but the output is much cleaner.
Pick whichever makes the most sense for your application! They are drop-in replaceable, so you can start with the AP63300 and then change over to the AP63301 if you need a quieter supply.
Whichever you pick, there are thousands in stock right now at Digi-Key, along with eval boards for both the AP63300 and AP66331 with nice layouts and 2 oz thick copper so you can really ‘stress’ the design to make sure it can supply the currents you need.
Order some AP63300 from Digi-Key today, and you can have it in hand tomorrow morning – we got our chips today and will start doing a test layout this weekend!
See on Digi-Key at https://www.digikey.com/short/4tfv04