High-Power PA Operation at Temperatures Below -20°C May Affect the 32-kHz Crystal Oscillator
Revisions Affected:
Revision B
Details:
When using the high-power PA at temperatures below -20°C and high output power, the PA may affect
the 32-kHz crystal oscillator due to RF load impedance mismatch. In this situation the crystal oscillator will stop, and provided the clock loss
detector is enabled (OSC_DIG:CTL0.CLK_LOSS_EN = 1), the device will reset. Antenna impedances outside of VSWR of 2:1 must be avoided in all
operating scenarios.
Workaround:
- For applications operating below -20°C, it is of particular importance to accurately follow
the reference design for the RF balun and -matching network with respect to component values and layout. Amplitude- and phase balance
through the balun must be <1dB and <6 degrees, respectively.
- For PCB designs not adhering to the TI recommended guidelines or in applications where
antenna impedance is subject to change due to external factors, output power should be limited to 17 dBm maximum.
- Make sure the clock loss detector is enabled, OSC_DIG:CTL0.CLK_LOSS_EN = 1, to properly reset
the device should the crystal oscillator be stopped.