Undervoltage (Safe Prepare Mode) - Siemens VDO DTCO 1381 Technical Description

14.1 Operating conditions of the DTCO 1381

14.1.2 Undervoltage (Safe Prepare Mode)

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Standby mode is cancelled by the following conditions:
• The ignition of the vehicle (terminal 15) is switched on.
• Any button is actuated.
• The DTCO 1381 detects motion sensor pulses.
• Failure of the voltage supply of the DTCO 1381 / motion sensor.
• The housing switch of the DTCO 1381 is actuated, i.e. the
housing is opened.
• The DTCO 1381 detects and announces an event or a fault.
If the voltage supply of the DTCO 1381 drops below the following
minimum value of the specified range, the DTCO 1381 switches to
the "undervoltage" mode:
• 12 V version: typ. 10,0 V (min. 9,4 V; max. 10,2 V)
• 24 V version: typ. 14,0 V (min. 13,4 V; max. 14,6 V)
Current consumption is limited to ensure that the system can be
shut down reliably if the voltage drops further.
The following functions are not available:
• The backlighting of the display is switched off.
• Printing or display of data is not possible.
• Insertion or removal of the tachograph cards is not possible.
As soon as the voltage supply of the DTCO 1381 increases once
more to above the following limit value into the specified range, the
DTCO 1381 returns to the normal operating mode:
• 12 V version: typ. 10,6 V ± 1 %
• 24 V version: typ. 16,0 V ± 1 %
If the supply voltage of the DTCO 1381 drops further, the DTCO 1381
switches to the "power interruption" mode.
© Siemens VDO Automotive AG
Appendix
Edition 07/2007