
EM358x
38
Rev. 0.4
Table 5-1. POR HV Thresholds
Parameter
Test conditions
Min
Typ
Max
Unit
Always-on domain release
0.62
0.95
1.20
V
Always-on domain assert
0.45
0.65
0.85
V
Supply rise time
From 0.5 V to 1.7 V
250
µs
Table 5-2. POR LVcore Thresholds
Parameter
Test conditions
Min
Typ
Max
Unit
1.25 V domain release
0.9
1.0
1.1
V
1.25 V domain assert
0.8
0.9
1.0
V
Table 5-3 POR LVmem Thresholds
Parameter
Test conditions
Min
Typ
Max
Unit
1.8 V domain release
1.35
1.5
1.65
V
1.8 V domain assert
1.26
1.4
1.54
V
The POR LVcore and POR LVmem reset sources are merged to provide a single reset source, POR LV, to the
Reset Generation module, since the detection of either event needs to reset the same system modules.
5.2.1.2
nRESET Pin
A single active low pin, nRESET, is provided to reset the system. This pin has a Schmitt triggered input.
To afford good noise immunity and resistance to switch bounce, the pin is filtered with the Reset Filter module
and generates the pin reset source, nRESET, to the Reset Generation module. Table 5-4 contains the
specification for the filter.
Table 5-4. Reset Filter Specification for nRESET
Parameter
Min
Typ
Max
Unit
Reset filter time constant
2.1
12.0
16.0
µs
Reset pulse width to guarantee a reset
26.0
µs
Reset pulse width guaranteed not to cause a reset
0
1.0
µs
5.2.1.3
Watchdog Reset
The EM358x contains a watchdog timer (see also the Watchdog Timer section) that is clocked by the internal
1 kHz timing reference. When the timer expires it generates the reset source WATCHDOG_RESET to the Reset
Generation module.
5.2.1.4
Software Reset
The ARM
®
Cortex
TM
-M3 CPU can initiate a reset under software control. This is indicated with the reset source
SYSRESETREQ to the Reset Generation module.
5.2.1.5
Option Byte Error
The flash memory controller contains a state machine that reads configuration information from the information
blocks in the flash at system start time. An error check is performed on the option bytes that are read from flash
and, if the check fails, an error is signaled that provides the reset source OPT_BYTE_ERROR to the Reset
Generation module.
Summary of Contents for EMBER EM358 series
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