MC55i Terminal Hardware Interface Description
3.5 Power Supply
32
MC55i_Terminal_HD_v01.201a
Page 22 of 47
2010-04-16
Confidential / Released
3.5
Power Supply
The power supply of the MC55i Terminal has to be a single voltage source of V
PLUS
=8V…30V
capable of providing a peak current (pulsed 2x577ms at T=4.615ms) of about 1.2A at 12V dur-
ing an active transmission. The uplink burst causes strong ripple (drop) on the power lines. The
drop voltage should not exceed 1V, but the absolute minimum voltage during drops must be
>7.6V.
The MC55i Terminal is protected from supply voltage reversal and overvoltage. An internal fuse
that is not removable is intended for electrical safety according to EN60950. An external fast
acting fuse >0.4A with melting integral I
2
t (0.15 … 0.25)A
2
s is necessary to use the MC55i Ter-
minal at a 12V or 24V power supply system for vehicles.
The power supply must be compliant with the EN60950 guidelines.
A switching regulator regulates the input voltage for the internal supply. In POWER DOWN
mode the switching regulator is turned off by the On/Off logic. A separate voltage regulator sup-
plies the real time clock (RTC) in the GSM engine.
When power fails for >1ms, MC55i Terminal resets or switches off. When power fails for >15s
the RTC will be reset.
Figure 4:
6-pole Western jack for power
supply, ignition, power down
Mains adapter: If it fits into the
design of your GSM application
we recommend the plug-in sup-
ply unit used with the type ap-
proved Cinterion reference setup. Ordering information can be found in
. This 12V
mains adapter comes with a 6-pole Western plug and provides an internal connection between
IGT_IN pin and PLUS pin for auto ignition (power up).
Table 9:
Female 6-pole Western plug for power supply, ignition, power down
Pin
Signal name
Use
Parameters
1
PLUS
Power supply
8V – 30V DC, max. 33V for 1 min
2
free
---
---
3
PD_IN
Signal for POWER DOWN mode U
IH
> 5V for t>100ms turns the terminal off.
U
IL
<2V and low level for normal operation.
4
IGT_IN
Ignition
U
IH
>5V
Ignition >5V for more than 200ms switches
the MC55i Terminal on. Ignition is activated
only by a rising edge. The rise time is
<20ms
5
free
---
---
6
GND
Ground
0V
Pin assignment:
2 free
5 free
1 +
3 PD_IN
4 IGT_IN
6 GND
5
6
1
2
3
4
