Motorola SE4750, Integration Manual

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Installation 2 - 3
Figure 2-1
Lumped Capacitance Thermal Model of SE4750 Scan Engine
Based on this lumped capacitance thermal model and the engine power consumptions (see Table 3-7 on page
3-8 ), the allowed engine scanning duty cycles can be calculated and plotted for a defined engine chassis
temperature limit as Figure 2-2 and Figure 2-3 .
Figure 2-2
Engine Scanning Duty Cycle in Level Trigger Mode, Chassis Temperature Limit = 60°C
Notes:
•
The plot represents the condition that the engine is in still air and with no heat sink attached, while the air
temperature is measured as the ambient temperature.
•
The scanning time is measured between the trigger event (pulling the trigger) and the end of the scanning
session (decoding).
•
The scanning duty cycle is the percentage of time when the engine is in full scanning mode.
•
0% scanning duty cycle in level trigger mode indicates that the engine is at idle.
•
The number of scans per minute is based on the assumption that a typical scanning session requires
1 second of full scanning power. For example, 12 scans per minute equals 20% scanning duty cycle.