8.2.1 System Power-Up
At power-up, from a power supply sequencing perspective, the SAM9X60D1G-I/LZB power
supplies are categorized into five independent groups:
- 5V_MAIN (main supply)
- VDDBU (backup group)
- VDD_3V3 (periphery group) containing VDDUTMII, VDDANA, VDDOSC, VDDNF, VDDIOPx and VDDQSPI inputs
- VDDIOM (memory group)
- VDDCORE (core group)
The figure below shows the recommended power-up sequence. Note the following:
- VDDBU
- When supplied from a precharged storage element (battery, supercapacitor or micro-battery), VDDBU is an always-on supply input and is therefore not part of the power supply sequencing.
- When no storage element is used on VDDBU in the application, VDDBU must be tied to VDD_3V3.
- When a supercapacitor or a micro-battery is used in the application to power VDDBU in Backup mode, this element must be isolated from VDDBU during its (slow) charge, so that VDDBU closely follows VDD_3V3. In table Power-Up Timing Specification, the parameter t1 limits the delay to establish VDDBU after VDD_3V3.
- VDDOUT25 is the output of the internal 2.5V regulator, and therefore there is no power supply requirement on this pin. VDDOUT25 is automatically started at VDD_3V3 rise when VDD_3V3 is above its Power-On-Reset threshold.
Note:
- If VDDQSPI is supplied externally, the power must be applied at the same time or after the presence of VDD_3V3 and before the presence of VDDIOM.
| Symbol | Parameter | Conditions(1) | Min | Typ | Max | Unit |
|---|---|---|---|---|---|---|
| t0 | nSTRT deglitch time | nSTRT pin falling edge | 0.5 | – | – | ms |
| t1 | VDDBU delay | Delay from established VDD_3V3 to established VDDBU | – | – | 0.2 | ms |
| t2 | VDD_3V3 to Periphery group delay | Delay from established VDD_3V3 to the periphery group established supply | – | 8 | – | ms |
| t3 | Periphery group to VDDCORE delay | Delay from the periphery group established supply to the VDDCORE supply turn-on | – | 4 | – | ms |
| t4 | Reset delay at power-up | From established VDDCORE to NRST high | – | 16 | – | ms |
Note:
- The term "established" refers to a power supply established to 90% of its final value.