User's Manual

AC65/AC75 Hardware Interface Description

Confidential / Preliminary

AC65/AC75_hd_v00.372 Page 28 of 118 2006-08-03

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 Chapter 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 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+CALA, Airplane mode and AT+IPR can

be found in [1].

3.3.1.1 Turn on AC65/AC75 Using Ignition Line IGT

When AC65/AC75 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/collector 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 Chapter 3.5.6.