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AC75 Hardware Interface Description
Strictly confidential / Preliminary
s
AC75_HD_V00.202
Page 28 of 120
27.04.2006
EMERG_RST
PWR_IND
t = 400ms
min
>
120ms
BATT+
IGT
HiZ
VEXT
TXD0/TXD1/RTS0/RST1/DTR0 (driven by the application)
CTS0/CTS1/DSR0/DCD0
Interface pins
Undefined
Defined
ca. 500 ms
Figure 6: Power-on with IGT held low before switching on operating voltage at BATT+
If the IGT line is driven low for less than 400ms the module will, instead of starting up, send
only the alert message “SHUTDOWN after Illegal PowerUp” to the host application. The alert
message appears on the serial interfaces ASC0 and ASC1 at a fixed bit rate of 115200bps. If
other fixed bit rates or autobauding are set, the URC delivers only undefined characters. The
message will not be indicated on the USB interface.