Buck output capacitor sizing

Hypothesis:

• 50mV output ripple max (absolute maximum rating in STM32F042K6 datasheet)
• 100mA max consumption (STM32F042K6 + BT) -> Ipk = 2 x Iout_max = 200mA
• Switching frequency 40kHz

This gives a current ripple of 200mA, and a minimum value of 12.5µF for the output capacitor. Chosen model : Multicomp MCVVT035M101EA6L, 6.3V / 100µF (ok), Ripple current 50mA (NOK)

With 100µF -> Vout_ripple = 6.25mV

Other models:

• Panasonic EEEFK0J101P / EEEFK0J101AP (100µF / 6.3V / size D / 240mA ripple) - FA 2254316 .31€ / FA 1244389 .46€
• Panasonic EEEFC1A101AP / EEEFC1A101P (100µF / 10V / size E / 230mA ripple)
• Panasonic EEEFT1A151AR (150µF / 10V / size C / 240mA ripple)
• Panasonic EEEFT1A221AP (220µF / 10V / size D / 300mA ripple)
• Panasonic EEEFPJ101UAR (100µF / 6.3V / size C / 240mA)
• Panasonic EEEFP0J101AP (100µF / 6.3V / size D / 300mA) - FA 1539453 .48€
• Panasonic EEETC1C101XP (100 µF / 16V / size D / 300mA)
• Multicomp MCVKZ6R3M101EA1L (100µF / 6.3V / size D / 230mA) - FA 2611349 .12€
• Würth 865080243007 (100µF / 10V / size D / 240mA) - FA 2466265 .36€
• Würth 865080243006 (68µF / 10V / size D / 220mA) - FA 2466264 .36€
• Würth 865060143004 (100µF / 6.3V / size D / 240mA) - FA 2466169 .26€
• Polymer / hybrid polymer (expensive)