Revisions Affected:

Revision C

Details:

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

When using the +14dBm RF power amplifier

• ARIB T-108 (Japan)

When using the +20dBm RF power amplifier

• FCC CFR47 Part 15 (US)
• ETSI EN 300 220 (Europe)
• ETSI EN 300 328 (Europe)
• ETSI EN 300 440 (Europe)

Workaround:

For compliance with affected standards, external load capacitors might be needed for the 48MHz crystal to reduce spurious emissions. Internal capacitors (default 7pF 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 the examples:

#define SET_CCFG_MODE_CONF_XOSC_CAPARRAY_DELTA -128 
#define SET_CCFG_MODE_CONF_XOSC_CAP_MOD 0