Power Supply Noise; Thermal Considerations - Motorola PL3307 Integration Manual

2 - 2 PL3307 Decoder Integration Guide

Power Supply Noise

For reliable operation a low-noise power supply is required. Pay close attention to power supply quality and
testing to ensure the best performance from the PL3307 and imager engine components.
5V Host: For a host that supplies 5 VDC (HOST_5V or USB2_5V) to the decoder, the decoder maintains
proper regulation and supply quality.
3.3V Host: For a host that provides power via the HOST_3P3 connection, the power supply passes directly
through the decoder module to the imager engine. In bar code applications, up to 100 mV peak-to-peak noise
is acceptable on the 3.3V supply (10 Hz to 100 kHz). For image capture applications, limit power supply noise
to 30 mV peak-to-peak across the same frequency range. To achieve improvements in both image quality and
decode performance, provide additional filtering of the HOST_3P3 supply. Carefully review both the efficiency
and current delivering capacity of the regulator.

Thermal Considerations

The PL3307 decoder module includes several high-power components that dissipate heat during operation.
These components can exhibit high temperatures when the PL3307/imager engine pair is running at 60 frames
per second with full illumination. Use care when integrating the PL3307/imager engine pair into the target
application.
Protective measures that reduce power consumption and/or facilitate heat removal within a target system
include but are not limited to:
•
Using reduced frame rates (e.g., 15 fps)
•
Reducing illumination intensity on the imager engine
•
Mounting the PL3307 to a solid metallic surface using metal screws
•
Selecting a housing design that allows for natural or forced convection.
Note that running the PL3307/imager engine pair in continuous 60 fps with both aiming and illumination
enabled full time is highly uncommon. Typical decoding and image capture applications are low duty cycle
operations and internal temperature rise due to the PL3307/imager engine pair should be minimal.