Data Sheet

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FORM NO.: FR2-015_ A Responsible Department：WBU Expiry Date: Forever
The information contained herein is the exclusive property of AzureWave and shall not be distributed, reproduced, or disclosed
in whole or in part without prior written permission of AzureWave.
3.7 Frequency Reference
An external crystal is used for generating all radio frequencies and normal operation clocking. As an
alternative, an external frequency reference driven by a temperature-compensated crystal oscillator
(TCXO) signal may be used. No software settings are required to differentiate between the two. In
addition, a low-power oscillator (LPO) is provided for lower power mode timing.
External 32.768KHz Low-Power Oscillator
The AW-CM390SM uses a secondary low frequency clock for low-power-mode timing. Either the
internal low- precision LPO or an external 32.768 kHz precision oscillator is required. The internal
LPO frequency range is approximately 33 kHz ± 30% over process, voltage, and temperature, which
is adequate for some applications. However, one trade-off caused by this wide LPO tolerance is a
small current consumption increase during power save mode that is incurred by the need to wake-
up earlier to avoid missing beacons. Whenever possible, the preferred approach is to use a precision
external 32.768 kHz clock that meets the requirements listed in below.