User's Manual

microNode Integration Specification Power States
On-Ramp Wireless, Inc. 24 014-0033-00 Rev. H
5.1.2 Deep Sleep State
The microNode shuts off all its power regulators except a couple low quiescent LDO regulators.
These regulators keep a minimal amount of circuitry alive for tracking network timers, enable a
32 kHz clock, and some minor interface circuitry.
5.1.3 Oscillator Calibration State
When the microNode is in Deep Sleep state, it attempts to maintain accuracy of its low power
32 kHz clock to enable faster network synchronizing when it wakes up. The CPU of the
microNode is not activated during this calibration state. The microNode will periodically (and
briefly) wake up in a very low power mode to calibrate its 32 kHz clock to its very accurate 26
MHz clock. This is especially important when the temperature varies substantially causing the 32
kHz oscillator to drift. This is illustrated in the following figure.
This plot is an example of the microNode performing a self-calibration of its 32 kHz oscillator.
The pulses represent the TCXO being turned on periodically to perform the calibration. The
microNode wakes itself from Deep Sleep, Calibrates, and then falls back to sleep. Minimal power
is consumed during this self-calibration process. As can be seen, the microNode does this
approximately every 900 seconds.
Figure 14. microNode Oscillator Calibration: Current (Amps) vs Time (Seconds)