Specifications

AC65/AC75 Hardware Interface Description

3.3 Power-Up / Power-Down Scenarios

AC65_AC75_HD_v01.002 Page 36 of 117 2006-10-30

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Be sure not to disconnect the supply voltage V

BATT+

before the URC “^SHUTDOWN” has been issued and the

PWR_IND signal has gone high. Otherwise you run the risk of losing data. Signal states during turn-off are shown

in Figure 8.

While AC65/AC75 is in Power-down mode the application interface is switched off and must not be fed from any

other source. Therefore, your application must be designed to avoid any current flow into any digital pins of the

application interface, especially of the serial interfaces. No special care is required for the USB interface which

is protected from reverse current.

Figure 8: Signal states during turn-off procedure

Note 1: Depending on capacitance load from host application

3.3.3.2 Leakage Current in Power-Down Mode

The leakage current in Power-down mode varies depending on the following conditions:

• If the supply voltage at BATT+ was disconnected and then applied again without starting up the AC65/AC75

module, the leakage current ranges between 90µA and 100µA.

• If the AC65/AC75 module is started and afterwards powered down with AT^SMSO, then the leakage current

is only 50µA.

Therefore, in order to minimize the leakage current take care to start up the module at least once before it is

powered down.

VEXT

See note 1

TXD0/TXD1/RTS0/RTS1/DTR0 (driven by the application)

Interface pins

Undefined

Defined

PWR_IND

CTS0/CTS1/DSR0/DTR0