EES3 Hardware Interface Description
3.3 Power Up / Power Down Scenarios
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EES3_HD_v01.100b
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2009-08-12
Confidential / Released
3.3
Power Up / Power Down Scenarios
In general, be sure not to turn on EES3 while it is beyond the safety limits of voltage and tem-
perature stated in
. EES3 would immediately switch off after having started and de-
tected these inappropriate conditions. In extreme cases this can cause permanent damage to
the module.
3.3.1
Turn on EES3
EES3 can be started in a variety of ways as described in the following chapters:
•
Hardware driven start-up by IGT line: starts Normal mode or Airplane mode (see
•
Software controlled reset by AT+CFUN command: starts Normal mode or Airplane mode
(see
•
Hardware driven start-up by VCHARGE line: starts charging algorithm and charge-only
mode (see
)
•
Wake-up from Power-down mode by using RTC interrupt: starts Airplane mode
The option whether to start into Normal mode or Airplane mode depends on the settings made
with the AT^SCFG command or AT+CALA. With AT+CALA, followed by AT^SMSO the module
can be configured to restart into Airplane mode at a scheduled alarm time. Switching back and
forth between Normal mode and Airplane mode is possible any time during operation by using
the AT^SCFG command.
After startup or mode change the following URCs indicate the module’s ready state:
•
“SYSSTART” indicates that the module has entered Normal mode.
•
^SYSSTART AIRPLANE MODE” indicates that the module has entered Airplane mode.
•
^SYSSTART CHARGE ONLY MODE” indicates that the module has entered the Charge-
only mode.
These URCs are indicated only if the module is set to a fixed bit rate, i.e. they do not appear if
autobauding is enabled (AT+IPR
0). Detailed explanations on AT^SCFG, AT+CFUN, AT+CA-
LA, Airplane mode and AT+IPR can be found in
3.3.1.1
Turn on EES3 Using Ignition Line IGT
When the EES3 module is in Power-down mode or Charge-only mode, it can be started to Nor-
mal mode or Airplane mode by driving the IGT (ignition) line to ground. This must be accom-
plished with an open drain/collector driver to avoid current flowing into this line.
The module will start up when both of the following two conditions are met:
•
The supply voltage applied at BATT+ must be in the operating range.
•
The IGT line needs to be driven low for at least 400ms in Power-down mode or at least 2s
in Charge-only mode.
Considering different strategies of host application design the figures below show two ap-
proaches to meet this requirement: The example in
assumes that IGT is activated after
BATT+ has already been applied. The example in
assumes that IGT is held low before
BATT+ is switched on. In either case, to power on the module, ensure that low state of IGT
takes at least 400ms (Power-down mode) or 2s (Charge-only mode) from the moment the volt-
age at BATT+ is available. For Charge-only mode see also
.
