Power Supply Noise - Motorola Symbol PL4507 Integration Manual

2 - 2 Symbol PL4507 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 PL4507 and SE4500 components.
5V Host: For a host that supplies 5 VDC (HOST_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 SE4500 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. To achieve optimal performance
use a low noise linear regulator; however consider that in certain applications the PL4507/SE4500 can draw as
much as 700 mA. Carefully review both the efficiency and current delivering capacity of the regulator.
Thermal Considerations
The PL4507 decoder module includes several high-power components that dissipate heat during operation. These
components can exhibit case temperatures as high as 25
running at 60 frames per second with full illumination. Use care when integrating the PL4507/SE4500 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 video frame rates (e.g., 15 fps)
•
Reducing illumination intensity on the SE4500
•
Mounting the SE4500 to a solid metallic surface and mounting the PL4507 to a similar surface using metal
screws
•
Selecting a housing design that allows for natural or forced convection.
Note that running the PL4507/SE4500 pair in continuous 60 fps video mode 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 PL4507/SE4500 pair should be minimal.
o
C above ambient when the PL4507/SE4500 pair is