CY8CKIT-030 PSoC® 3 Development Kit Guide, Doc. # 001-61038 Rev. *J
22
Hardware
Figure 4-7. Boost Converter
4.2.5
32-kHz and 24-MHz Crystal
PSoC 3 has an on-chip real time clock (RTC), which can function in sleep. This requires an external
32-kHz crystal, which is provided on the board to facilitate RTC-based designs. The PSoC 3 also
has an external MHz crystal option in applications where the IMO tolerance is not satisfactory. In
these applications, the board has a 24-MHz crystal to provide an accurate main oscillator.
4.2.6
Protection Circuit
A reverse-voltage and over-voltage protection circuit is added to the expansion port on the 5-V and
3.3-V lines.
The protection circuit consists of two P-channel MOSFET on the power line, allowing the current to
flow from input to output depending on the voltages applied at the external board connector.
Figure 4-8
and
Figure 4-9
are protection circuits placed between EBK and the onboard components
on the 5-V and 3.3-V lines.
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