High-Power PA Operation at Temperatures Below -20°C May Affect the 32-kHz Crystal
Oscillator
Revisions Affected:
Revision C and earlier
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.