Data Sheet

Q4000 Technical Data Sheet
Document 1135-0902, REV K 11
Load Dump Protection 2.4.3
To pass the load dump testing requirement of the J1455 specification, there must be a minimum of
two 33V diodes placed in parallel between power and ground of the input power supply. Load dump
protection is necessary to protect the modem from possible high voltage at startup. With some heavy
machinery at startup, the alternator voltage can jump quite high until it is pulled down into regulation.
The diodes shown here, placed in parallel between power and ground of the input power supply, act
to absorb this energy before it reaches the modem. In Figure 2-4 showing this Load Dump Protection
Circuit, we are using two “Littlefuse, Inc.” 5KP33A diodes.
Figure 2-4, Load Dump Protection Circuit
Typical Power Consumption 2.4.4
This section describes the typical power consumptions of each component of the Q4000 modem. Table 2-1,
Input Power Limits, is a listing of the required input voltage limits.
Table 2-1, Input Power Limits
Network Volts
ORBCOMM 10.5 - 32
Iridium 9 - 32
GlobalStar 6 - 32
Inmarsat 9 - 32
GSM/GPRS 6 - 32
GPS 6 - 32
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