MSEL and nCONFIG behavior at power up

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