6.4 Power Supply Configuration #4

Each power input of the SAMA5D27 SOM1 is supplied by separate power supplies.

  • Backup domain is connected to a coin cell.
  • Camera sensor power input (VDDISC) is connected to a separate power supply set at one of the following voltage levels (1.8V/2.5V/2.8V/3.0V or 3.3V) depending on the camera sensor technology used in the application.
  • SD Card power input (VDDSDHC) is connected to a separate power supply set at one of the following voltage levels (1.8V or 3.3V) depending on the SD Card Technology/Speed used in the application.
  • VDDIN_3V3 power input is connected to the main 3.3V supply.
In this configuration, the following PIOs have:
  • VDDBU Power Rail as reference
    • COMPP and COMPN
    • PIOBU1 to PIOBU7
    • RXD, SHDN and WKUP
  • VDDISC Power Rail as reference
    • PC9 to PC25
  • VDDSDHC Power Rail as reference
    • PA0 to PA10
  • All other PIOs have VDDIN_3V3 Power Rail as reference.
Figure 6-10. Power Configuration #4

In this configuration mode, the two following timing sequences are applied.

Figure 6-11. Power-On Sequence Timing Diagram
Figure 6-12. Power-Off Sequence Timing Diagram
Table 6-4. Timing Values
SymbolDescriptionMin.Typ.Max.Unit
tmainMain 3.3V Start-up Time (From regulator available on the mother board)––1ms
ton1VDDISC Regulator Start-up Time (From regulator available on the mother board)––800µs
ton2VDDSDHC Regulator Start-up Time (From regulator available on the mother board)––800µs
tstartInternal Delay before starting System Core Supplies1–3ms
tporPower-on Reset Delay–1011ms
tsysLow-speed to High-speed Card Timing(1)Depending on system on timems
tsoftSoftware Shutdown TimeDepending on system off timems
tmain_offMain 3.3V Power-off Time (From regulator available on the motherboard)––1ms
toff1VDDISC Regulator Power-off Time (From regulator available on the motherboard)––1ms
toff2VDDSDHC Regulator Power-off Time (From regulator available on the motherboard)––1ms
tstopInternal Delay before switching off System Core Supplies1–3ms
Note:
  1. Timing depends on the system boot time. No particular recommendations to apply.