Revisions Affected:

Revision C

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)

When using the +20-dBm RF power amplifier

• 470- to 510-MHz (China) Band
• 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 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 the examples:

#define SET_CCFG_MODE_CONF_XOSC_CAPARRAY_DELTA -128 
#define SET_CCFG_MODE_CONF_XOSC_CAP_MOD 0