Design Details — Power Supply
We’ve implemented a Microchip MCP16301T-based
power supply circuit instead of a pair of capacitors and a
three-terminal LDO voltage regulator IC stuck to a big
copper pad. The MCP16301T high voltage input
integrated switch step-down regulator is the prime player
in our step-down voltage regulator configuration. All of the
solid-state switching components are contained within the
MCP16301T’s tiny SOT- 23-6 package. The desired + 3. 3
VDC output voltage is determined by the 31.2K/10K
Printed Circuit Board
Screenshot 1 is a screen capture of the initial PCB
design. The design’s subsystems are laid out in their own
allotted copper domain. I purposefully didn’t lay out any
mounting holes. I’ll leave those up to you.
Note that I’ve applied a generous amount of ground
plane on both sides of the PCB. The ground plane serves
two purposes. It helps reduce the system’s electrical noise
and it acts as a unifying ground conductor for the top and
bottom board layers.
In the next installment of Design Cycle, we will mount
up all of our components. Once the PCB is totally stuffed,
we’ll write some code to bring each of our multipurpose
communications node’s subsystems to life. NV
July 2015 73
■ Schematic 6. This switcher is good for 600 mA. It
generates very little heat and takes up very little space.
■ Screenshot 1. This is our PCB design. The components
used were chosen to allow hand soldering techniques to
be applied in its construction. All of the parts are readily
available from vendors that advertise in Nuts & Volts.