Revisions Affected:

Revision E and earlier

Details:

When device internal load capacitors are used with the external 48-MHz crystal, energy couples from the crystal oscillator circuit to the RF output. This coupling causes spurious emissions at N × 48 MHz from carrier frequency. This includes, but is not limited to, the frequency bands supported by the device covered by the following regulations:

When using the +14-dBm RF power amplifier

• ARIB T-108 (Japan)

Workaround:

For compliance with affected standards, external load capacitors might be needed for the 48-MHz crystal to reduce spurious emissions. Internal capacitors (default 7-pF connected capacitance) must then be disconnected internally.

This workaround is implemented by defining the following symbols in the included customer configuration file (ccfg.c) available in all Software Development Kit (SDK) examples:
#define SET_CCFG_MODE_CONF_XOSC_CAPARRAY_DELTA -128
#define SET_CCFG_MODE_CONF_XOSC_CAP_MOD 0