2.4.1 Requirements

  • A 5.62 kΩ resistor is connected to the VBG pin for USB external tuning and an adequate voltage divider is placed on USB VBUS to transform the 5V into the PIO voltage.

    Refer to “Typical Connection” in sections “USB High Speed Device Port (UDPHS)” and “USB Host High Speed Port (UHPHS)” of the SAMA5D2 data sheet.

  • The TST pin is grounded.
  • If the design does not need JTAG boundary scan, tie the JTAGSEL pin to GND or leave it floating.
  • The SDCAL calibration cell input should be connected to ground with a 20 kΩ resistor for 1.8V SDMMC memories or a 16.9 kΩ resistor for 3.3V memories. If the memory device operates in both 1.8V and 3.3V modes, then use a 20 kΩ resistor.
  • A 32.768 kHz crystal is placed between XIN32 and XOUT32.

    Refer to section “32.768 kHz Crystal Oscillator Characteristics” in the “Electrical Characteristics” of the SAMA5D2 data sheet.

  • A high-frequency clock source is provided either through a crystal oscillator placed between XIN and XOUT or through an external clock generator.

    Refer to section “Main Oscillator Characteristics” in the “Electrical Characteristics” of the SAMA5D2 data sheet.

  • If the clock generator option is chosen, it is recommended to ground XOUT to improve stability.
  • Clock sources should be chosen with great care.

    Refer to section “Recommended Crystal Characteristics” in the “Electrical Characteristics” of the SAMA5D2 data sheet.