Specifications

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Chapter 4
Implementation
This chapter discusses the implementation path taken during th e course of this research
and project development. Th e requirements and elaborations expressed in Chapter 3 were
used to guide the selection of available hardware components. The selected components were
then assembled and specific operations verified. Once the verification process is complete,
the resulting d evice’s performance and functionality was tested. These test results are
shown in Chapter 5.
4.1 Hardware Analysis and Selection
The analysis of constraints or requirements that took place to realize a s atisfactory
hardware solution is contained in this section. The implementations of all the modules
depicted in Figure 3.1 are discussed here. Primarily, this section focuses on the tradeoffs
made during this phase.
4.1.1 Power Supply
To realize the hardware input and output requirements of this module, multiple IC’s
and tech nologies needed to be combined. Figure 4.1 shows the selected combination of
components. On the input side of this module, there are two separate input sources. Both
could supply power at any given instance, therefore the reverse voltage protection (RVP)
circuit must guarantee that each supply does not interfere with the other. All components
directly connected to the RVP circuit must normally operate in a range of 3.0-15.0V. These
devices include a 3.3V low drop out (LDO) linear regulator, a 3.3V s witching regulator,
an adjustable-output switching regulator, and a battery supervisor circuit. The 5.0V LDO
is connected to the output of the variable switcher, and therefore must be able to operate