SAMA5D2 datasheet(42/56 Pages) MICROCHIP

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8.3.2.2

Power-down Considerations

The figure below shows the SAMA5D2 LPDDR2 SIP power-down sequence that starts by asserting the NRST line

to 0. Once NRST is asserted, the supply inputs can be immediately shut down without any specific timing or order

except for DDRM_VDD12 and DDRM_VDD18. VDDBU may not be shut down if the application uses a backup

battery on this supply input. In applications where VDDFUSE is powered, it is mandatory to shut down VDDFUSE

prior to removing any other supply. VDDFUSE can be removed before or after asserting the NRST signal.

Figure 8-2. Recommended Power-down Sequence

RSTPD

VDDAUDIOPLL

VDDIOP0

VDDANA

VDDOSC

time

NRST

VDDIOP1

VDDIOP2

VDDISC

VDDSDMMC

DDRM_VDD18

VDDUTMII

No specific order and no

specific timing required

among the channels

except DDRM_VDD12

and DDRM_VDD18

VDDBU

VDDFUSE

VDDCORE

VDDPLLA

VDDHSIC

VDDUTMIC

DDRM_VDD12, VDDIODDR

Table 8-2. Power-down Timing Specification

Symbol

Parameter

Conditions

Min

Max

Unit

tRSTPD

Reset delay at power-down

From NRST low to the first supply turn-off

–

VDDFUSE delay at shut-down

From VDDFUSE < 1V to the first supply turn-off

–

DDRM_VDD12 to

DDRM_VDD18 delay

From DDRM_VDD12 zeroed to DDRM_VDD18

turn-off

–

LPDDR2 power-off delay

From NRST low to DDRM_VDD18 zeroed

–

2000

8.3.2.3

Backup Mode Entry (Shutdown)

The figure below shows the recommended power-down sequence to place the SAMA5D2 LPDDR2 SIP either in

Backup mode or in Backup mode with the LPDDR2 in self-refresh. The SHDN signal, an output of the Shutdown

Controller (SHDWC), signals the shutdown request to the power supply. This output is supplied by VDDBU that is

present in Backup mode. Placing the LPDDR2 memory in self-refresh while in Backup mode requires maintaining

VDDIODDR, DDRM_VDD18 and DDRM_VDD12 as well. One possible way to signal this additional need to the

power supply is to position one of the general-purpose I/Os supplied by VDDBU (PIOBUx) in a predefined state.

SAMA5D2 SIP

Electrical Characteristics

Datasheet

DS60001484D-page 42

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