Specifications

AC65/AC75 Hardware Interface Description

3.3 Power-Up / Power-Down Scenarios

AC65_AC75_HD_v01.002 Page 32 of 117 2006-10-30

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3.3.1.2 Configuring the IGT Line for Use as ON/OFF Switch

The IGT line can be configured for use in two different switching modes: You can set the IGT line to switch on

the module only, or to switch it on and off. The switching mode is determined by the parameter "MEShutdown/

OnIgnition" of the AT^SCFG command. This approach is useful for application manufacturers who wish to have

an ON/OFF switch installed on the host device.

By factory default, the ON/OFF switch mode of IGT is disabled:

To configure IGT for use as ON/OFF switch:

We strongly recommend taking great care before changing the switching mode of the IGT line. To ensure that

the IGT line works properly as ON/OFF switch it is of vital importance that the following conditions are met.

Switch-on condition:If the AC65/AC75 is off, the IGT line must be asserted for at least 400ms before being

released. The module switches on after 400ms.

Switch-off condition:If the AC65/AC75 is on, the IGT line must be asserted for at least 1s before being released.

The module switches off after the line is released.

The switch-off routine is identical with the procedure initiated by AT^SMSO,

i.e. the software performs an orderly shutdown as described in Section 3.3.3.1.

Before switching off the module wait at least 2 seconds after startup.

Figure 7: Timing of IGT if used as ON/OFF switch

3.3.1.3 Turn on AC65/AC75 Using the VCHARGE Signal

As detailed in Section 3.5.7, the charging adapter can be connected regardless of the module’s operating mode.

If the charger is connected to the charger input of the external charging circuit and the module’s VCHARGE pin

while AC65/AC75 is off, and the battery voltage is above the undervoltage lockout threshold, processor con-

trolled fast charging starts (see Section 3.5.6). AC65/AC75 enters a restricted mode, referred to as Charge-only

mode where only the charging algorithm will be launched.

During the Charge-only mode AC65/AC75 is neither logged on to the GSM network nor are the serial interfaces

fully accessible. To switch from Charge-only mode to Normal mode the ignition line (IGT) must be pulled low for

at least 2 seconds. When released, the IGT line goes high and causes the module to enter the Normal mode.