8.3.2.4 Backup Mode Exit (Wake-up)
The figure below shows the recommended power-up sequence to wake up the SAMA5D2 LPDDR2 SIP from Backup mode. Upon a wake-up event, the Shutdown Controller toggles its SHDN output back to VDDBU to request the power supply to restart. Except for VDDIODDR, DDRM_VDD18 and DDRM_VDD12 which may already be present if the LPDDR2 memory was placed in Self-refresh mode, this power-up sequence is the same one as presented in the figure “Recommended Power-up Sequence”. In particular, the definitions of Group 1 and Group 2 are the same.
| Symbol | Parameter | Conditions | Min | Max | Unit |
|---|---|---|---|---|---|
| t1 | Group 2 to Group 1 delay | Delay from the last Group 2 established(1) supply to the first Group 1 supply turn-on | 1 | – | ms |
| t2 | Group 1 delay | Delay from the first Group 1 established supply to the last Group 1 established supply | – | 1 | |
| t3 | DDRM_VDD18 to DDRM_VDD12 delay | Delay from the DDRM_VDD18 established to DDRM_VDD12 turn-on | 0 | – | |
| t4 | LPDDR2 power-on delay | Delay from DDRM_VDD18 turn-on to DDRM_VDD12 established | – | 20 | |
| tRSTPU | Reset delay at power-up | From the last established supply to NRST high | 1 | – |
Note:
- An “established” supply refers to a power supply established at 90% of its final value.