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Asaf_Bloch's avatar
Asaf_Bloch
Icon for New Contributor rankNew Contributor
2 days ago

MSEL and nCONFIG behavior at power up

Hallo  We used the Agilex5 device with Smart VID and AS configuration. The device configured OK, but lately I notice the MSEL pins and nCONFIG pull down during VCCIO_SDM (1.8V), see attached figure...
Power
Programmable Logic Device
FakhrulA_altera's avatar
FakhrulA_altera
Icon for Regular Contributor rankRegular Contributor
2 hours ago

Hi Asaf,
 

Thank you for the information.

A temporary low level or glitch on MSEL and nCONFIG while VCCIO_SDM is ramping can be normal. These SDM pins are not guaranteed to be at a defined logic level during power-up. For AS configuration, MSEL is sampled after power-on and then reused as active-low flash chip-select signals. Therefore, some board-to-board variation during the ramp may be observed.


If the pins reach the expected levels after VCCIO_SDM is stable and the device configures successfully, no further action is required.

Please confirm that:

  • MSEL[2:0] use the recommended 4.7 kΩ straps for the selected AS mode.
  • nCONFIG is correctly pulled up to VCCIO_SDM.
  • The QSPI flash is powered before or together with VCCIO_SDM.

If the low level remains after VCCIO_SDM and POR are stable, or configuration becomes intermittent, please send oscilloscope captures of VCCIO_SDM, MSEL[2:0], nCONFIG, and nSTATUS from both an affected and unaffected board, together with the relevant schematic section.


Regards, 
Fakhrul