Datasheet

1112
SAM9G25 [DATASHEET]
11032D–ATARM–10-Mar-2014
46.14 POR Characteristics
A general presentation of Power-On-Reset (POR) characteristics is provided in Figure 46-5.
Figure 46-5. General Presentation of POR Behavior
When a very slow (versus t
RES
) supply rising slope is applied on POR VDD pin, the reset time becomes negligible and the
reset signal is released when V
DD
rises higher than V
th+
.
When a very fast (versus
t
RES
) supply rising slope is applied on POR VDD pin, the voltage threshold becomes negligible
and the reset signal is released after
t
RES
time. It is the smallest possible reset time.
46.14.1 Core Power Supply POR Characteristics
46.14.2 Backup Power Supply POR Characteristics
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.
Dynamic
t
res
NRST
VDD
V
th+
V
th
-
Vop
Static
Vnop
Table 46-28. Core Power Supply POR Characteristics
Symbol Parameter Conditions Min Typ Max Unit
V
th+
Threshold Voltage Rising Minimum Slope of +2.0V/30ms 0.5 0.7 0.89 V
V
th-
Threshold Voltage Falling Minimum Slope of +2.0V/30ms 0.4 0.6 0.85 V
t
RES
Reset Time 30 70 130 µs
I
DD
Current consumption After t
RES
37µA
Table 46-29. Backup Power Supply POR Characteristics
Symbol Parameter Conditions Min Typ Max Unit
V
th+
Threshold Voltage Rising Minimum Slope of +2.0V/30ms 1.42 4.52 1.62 V
V
th-
Threshold Voltage Falling Minimum Slope of +2.0V/30ms 1.35 1.45 1.55 V
t
RES
Reset Time
V
DDBU
is 3.3V 30 80 220
µs
V
DDBU
is 1.8V 40 100 330
I
DD
Current consumption After t
RES
68.5µA