Specifications

AC65/AC75 Hardware Interface Description
3.3 Power-Up / Power-Down Scenarios
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AC65_AC75_HD_v01.002 Page 29 of 117 2006-10-30
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3.3 Power-Up / Power-Down Scenarios
In general, be sure not to turn on AC65/AC75 while it is beyond the safety limits of voltage and temperature stated
in Section 5.1. AC65/AC75 would immediately switch off after having started and detected these inappropriate
conditions. In extreme cases this can cause permanent damage to the module.
3.3.1 Turn on AC65/AC75
AC65/AC75 can be started in a variety of ways as described in the following sections:
• Hardware driven start-up by IGT line: starts Normal mode or Airplane mode (see Section 3.3.1.1)
• Software controlled reset by AT+CFUN command: starts Normal mode or Airplane mode (see Section
3.3.1.4)
• Hardware driven start-up by VCHARGE line: starts charging algorithm and charge-only mode (see Section
3.3.1.3)
• 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 Air-
plane 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+CALA, Airplane mode and AT+IPR can be found in [1].
3.3.1.1 Turn on AC65/AC75 Using Ignition Line IGT
When the AC65/AC75 module is in Power-down mode or Charge-only mode, it can be started to Normal mode
or Airplane mode by driving the IGT (ignition) line to ground. This must be accomplished with an open drain/col-
lector driver to avoid current flowing into this pin.
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. When released IGT goes high and causes the module to start.
Considering different strategies of host application design the figures below show two approaches to meet this
requirement: The example in Figure 5 assumes that IGT is activated after BATT+ has already been applied. The
example in Figure 6 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 voltage at BATT+ is available. For Charge-only mode see also Section 3.5.7.
Assertion of CTS indicates that the module is ready to receive data from the host application. In addition, if con-
figured to a fixed bit rate (AT+IPR
≠0), the module will send the URC "^SYSSTART" or "^SYSSTART AIRPLANE
MODE" which notifies the host application that the first AT command can be sent to the module. The duration
until this URC is output varies with the SIM card and may take a couple of seconds.
Please note that no "^SYSSTART" or "^SYSSTART AIRPLANE MODE" URC will be generated if autobauding
(AT+IPR=0) is enabled.
To allow the application to detect the ready state of the module we recommend using hardware flow control which
can be set with AT\Q or AT+ICF (see [1] for details). The default setting of AC65/AC75 is AT\Q0 (no flow control)