Buck converter design: 3.3-5V input, ~2.8V output, < 10mA, tiny - Page 1
Forum section: electronics / projects

author: Saimoun
author_rank: Frequent Contributor
timestamp: May 07, 2025, 11:36:38 am
content: HiI would like a bit of help designing a Buck converter.It's a tiny tiny design, so the smaller and cheaper the better.The buck will only power a small MCU running an ADC and a UART (using the RC-internal oscillator).My estimation is that the current consumption will be < 1mA 95% of the time, and once in a while it might spike up to ~10ma.The output voltage can be anything between 2.4V and 3.3V which is what the MCU requires.I do not have tons of experience designing converters so if anyone has some IC suggestions, design suggestions, or general comments/considerations, I would love to hear them.Alternatively I could use an LDO if there is one with very low quiescent current?Thanks!

author: Saimoun
author_rank: Frequent Contributor
timestamp: May 07, 2025, 12:07:18 pm
content: Ha nevermind - the LDOs have crazy low ground current, so I think I'll go with that instead

author: xvr
author_rank: Frequent Contributor
timestamp: May 07, 2025, 12:10:52 pm
content: Quotehttps://www.digikey.ie/en/products/filter/voltage-regulators-linear-low-drop-out-ldo-regulators/699?s=N4IgjCBcoCwdIDGUBmBDANgZwKYBoQB7KAbRAGYYB2GciAXQIAcAXKEAZRYCcBLAOwDmIAL4EwAJgCcUUMkjps%2BIqXAAOGAAYAbGpAEJ5NWE0QD26WHL6QEqlSkabEtVWnabuteWuMQrdi4%2BIVECaipZJFRMXAJiSDIJTQACfgBBGwBWFPTPHIyDbNSCik18my1ygk0AOkzkgFaS7KqQTPJW2vbG5rVOmu0ezz7im1rdIYIqMtGCPv6pSZApGdzxIb8AyBAAVX5eFgB5FABZHDQsAFduHFDwHUzI%2BUVYlQTwEE22bYARQkuAEYYW5icD2GQIZ4xZTxMhWUxUDzichJTQRZHUXQ2KzaMDTbHkKjkKRmWyaCQWdFgsBSWnYmhgMCPL6BHgCYSgmlqCFyaJKOKqTSfUEAWgkTygPEuMNUzJEoI8CF4ABN2CKTKStiAbCwAJ5MW7bC7IeVAA

author: mariush
author_rank: Super Contributor
timestamp: May 07, 2025, 02:13:30 pm
content: You could probably go crazy with a MIC23030 :https://www.digikey.com/en/products/detail/microchip-technology/MIC23030-AYMT-TR/1878886Input Voltage: 2.7V to 5.5V• 400 mA Output Current• Up to 91% Efficiency and 83% at 1 mA• 21 µA Typical Quiescent Current• 8 MHz PWM Operation in Continuous Mode• Ultra-Fast Transient Response• Low Voltage Output Ripple- 14 mVPP Ripple in HyperLight Load® Mode- 5 mV Output Voltage Ripple in Full PWMMode• Fully Integrated MOSFET Switches• 0.01 µA Shutdown Current• Thermal Shutdown and Current-Limit Protection• Fixed and Adjustable Output Voltage OptionsAvailable• 1.6 mm x 1.6 mm 6-Lead TDFN Package• –40°C to +125°C Junction Temperature RangeSome lower frequency stuff ... TPS629203https://www.digikey.com/en/products/detail/texas-instruments/TPS629203DRLR/16516661High-efficiency DCS-Control topology– Internal compensation– Seamless PWM/PFM transition• 4-µA typical low quiescent current• Output current up to 0.3 A• RDSON: 250-mΩ high side, 85-mΩ low side• Output voltage accuracy of ±1%• Configurable output voltage options:– VFB external divider: 0.6 V to 5.5 V– VSET internal divider:• 18 options between 0.4 V and 5.5 V• Flexibility through the MODE/S-CONF pin– 2.5-MHz or 1.0-MHz switching frequency– Forced PWM or auto (PFM) power save modewith dynamic mode change option– Output discharge on/off• No external bootstrap capacitor required• Overcurrent and overtemperature protection• 100% duty cycle mode• Precise enable input• Power-good output• Pin-to-pin compatible with the TPS629210 andTPS629206 devices• 0.5-mm pitch, 8-pin SOT-5X3 package