User's Manual

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POWER SUPPLY
WSM2400 is powered from a single pin, VSUPPLY, which powers the I/O cells and is also used to
generate internal supplies. WSM2400’s two on-chip DC/DC converters minimize WSM2400’s energy
consumption while the device is awake. To conserve power the DC/DC converters are disabled when the
device is in low power state. WSM2400’s power supply conditioning architecture, including the two
integrated DC/ DC converters and three integrated low dropout regulators, provides excellent rejection
of supply noise. WSM2400’s operating supply voltage range is high enough to support direct connection
to lithium-thionyl chloride (Li-SOCl2) sources and wide enough to support battery operation over a
broad temperature range.
Figure 19. WSM2400 block diagram
SUPPLY MONITORING AND RESET
WSM2400 integrates a Power-on Reset (PoR) circuit. As the RESETn input pin is nominally configured
with an internal pull-up resistor, no connection is required. For a graceful shutdown, the software and
the networking layers should be cleanly halted via API commands prior to assertion of the RESETn pin.