Atmel Evaluation Kit AT91SAM9X25-EK AT91SAM9X25-EK Hoja De Datos
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AT91SAM9X25-EK
1104
SAM9X25 [DATASHEET]
11054E–ATARM–10-Mar-2014
46.15 Power Sequence Requirements
The AT91 board design must comply with the power-up guidelines below to guarantee reliable operation of the device.
Any deviation from these sequences may prevent the device from booting.
Any deviation from these sequences may prevent the device from booting.
46.15.1 Power-Up Sequence
Figure 46-6. V
DDCORE
and V
DDIO
Constraints at Startup
V
DDCORE
and V
DDBU
are controlled by internal POR (Power-On-Reset) to guarantee that these power sources reach their
target values prior to the release of POR.
V
DDIOP
must be
≥ V
IH
(refer to DC characteristics,
, for more details), (t
RES
+ t
1
) at the latest, after
V
DDCORE
has reached
V
th+
.
V
DDIOM
must reach V
OH
(refer to DC characteristics,
, for more details), (t
res
+ t
1
+ t
2
) at the latest, after
V
DDCORE
has reached
V
th+
.
t
RES
is a POR characteristic
t
1
= 3
×
t
SLCK
t
2
= 16
×
t
SLCK
The t
SLCK
min (22 µs) is obtained for the maximum frequency of the internal RC oscillator (44KHz).
t
RES
= 30 µs
t
1
= 66 µs
t
2
= 352 µs
V
DDPLL
is to be established prior to V
DDCORE
to ensure the PLL is powered once enabled into the ROM code.
As a conclusion, establish V
DDIOP
and V
DDIOM
first, then V
DDPLL
, and V
DDCORE
last, to ensure a reliable operation of the
device.
V
DD
(V)
Core Supply POR Output
VDDIOtyp
V
IH
V
th+
t
SLCK
t
res
V
DDIO
> V
IH
V
DDCORE
V
DDIO
t
1
VDDCOREtyp
V
OH
V
DDIO
> V
OH
t
2