SWRU626 December 2025 CC3501E , CC3551E
The device supports the external/stacked Flash and/or PSRAM.
The external memory signals are multiplexed on the following IO rings:
When stacked PSRAM is used then the VIO2 and VDDSF need to be driven by the same supply.
The following table describes the external memory topology and the VDDSF/VIO2 voltage level implications.
| # | Topology(1) | Description | Flash | PSRAM | XiP Mode Common for both Flash + PSRAM(4) | VDDSF | VIO2(2) |
|---|---|---|---|---|---|---|---|
| 1 | External Flash QSPI | External Flash only QSPI |
External QSPI |
None | Flash: QSPI, 40/80MHz, SDR/DDR | 1.8V or 3.3V | Independent 1.8 or 3.3V |
| 2 | External Flash Octal SPI | External Flash only Octal SPI |
External Octal SPI |
None | Flash: OSPI, 40/80MHz, SDR/DDR | 1.8V or 3.3V |
Same as VDDSF (D[7:4] on VIO2) |
| 3 |
Stacked Flash QSPI |
Stacked Flash, No PSRAM support |
Stacked QSPI |
Not Supported | Flash: QSPI, 40/80MHz, SDR/DDR |
1.8V only (Stacked Flash is 1.8V only) |
Independent 1.8 or 3.3V |
| 4 |
External Flash QSPI + Stacked PSRAM QSPI |
Stacked PSRAM + External Flash (Stacked PSRAM only is not supported) |
External QSPI |
Stacked QSPI |
Flash: QSPI, 80MHz, SDR/DDR PSRAM: QSPI, 80MHz, DDR |
1.8V only (Stacked PSRAM is 1.8V only) |
1.8V(3) (PSRAM CS on VIO2) |
| 5 |
External Flash Octal SPI +Stacked PSRAM QSPI |
Stacked PSRAM + External Flash (Stacked PSRAM only is not supported) |
External Octal SPI |
Stacked QSPI | Flash: OSPI, 40/80MHz, SDR/DDR PSRAM: QSPI, 80MHz, DDR |
1.8V only (Stacked PSRAM is 1.8V only) |
1.8V(3) (PSRAM CS on VIO2) |