Power Interruption (Safe Mode) - Siemens VDO DTCO 1381 Technical Description

14.1 Operating conditions of the DTCO 1381

14.1.4 Power interruption (Safe Mode)

14 - 6
If the voltage supply of the DTCO 1381 drops below the following
critical value of the specified range, the DTCO 1381 switches to the
"power interruption" mode:
• 12 V version: typ. 6,6 V (min. 6,0 V; max. 7,2 V)
• 24 V version: typ. 7,5 V (min. 6,9 V; max. 8,1 V)
In the "power interruption" mode the DTCO 1381 cannot fulfil its
function as EC recording equipment!
The following functions are not available:
• The driver's activities will not be recorded.
• The speed is not indicated.
• The backlighting of the display is switched off.
• All buttons are deactivated.
• All external interfaces are deactivated (except the v-pulse
outputs and the 4 pulses/m signal output).
• Printing or display of data is not possible.
• Insertion or removal of the tachograph cards is not possible.
If the supply voltage of the DTCO 1381 rises once more above the
critical value for the operating mode "power interruption", the
DTCO 1381 signals "power interruption".
As soon as the supply voltage of the DTCO 1381 increases to above
the following limit value, the DTCO 1381 switches to the "under-
voltage" mode:
• 12 V version: typ. 7,2 V (min. 6,6 V; max. 7,8 V)
• 24 V version: typ. 8,1 V (min. 7,5 V; max. 8,7 V)
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 %
© Siemens VDO Automotive AG
Appendix
Edition 07/2007