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KDJEM.1
KDJEM.1
Technical Moderator
November 28, 2024

Recommendations for the external capacitor on VCAP pin (STM32U5)

  • November 28, 2024
  • 0 replies
  • 1206 views

Defining VCAP

VCAP is the digital core supply provided by the internal LDO regulator. VCAP pins are present only on LDO packages (without SMPS).

STM32U5 external capacitor on VCAP pin recommendations

For the STM32U5 series, the external capacitor on VCAP pin requires the following characteristics:

  • COUT = 4.7 µF or 2 × 2.2 µF ±20%
  • COUT ESR < 20 mΩ at 3 MHz
  • COUT rated voltage ≥ 10 V

The COUT rated voltage must be greater than or equal to 10 V:

  • To ensure that the degradation of the DC bias at 3 V is small
  • To have the optimum working environment

Note: In the UFBGA169 package, when two VCAP pins are available, each pin must be connected to a 2.2 µF capacitor, for a total capacitance around 4.4 µF.

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