SX1231
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
3.3.4. Lock Time
PLL lock time TS_FS is a function of a number of technical factors, such as synthesized frequency, frequency step, etc.
When using the built-in sequencer, the SX1231 optimizes the startup time and automatically starts the receiver or the
transmitter when the PLL has locked. To manually control the startup time, the user should either wait for TS_FS max given
in the specification, or monitor the signal PLL lock detect indicator, which is set when the PLL has is within its locking
range.
When performing an AFC, which usually corrects very small frequency errors, the PLL response time is approximately:
5
-------------------
TPLLAFC
=
PLLBW
In a frequency hopping scheme, the timings TS_HOP given in the table of specifications give an order of magnitude for the
expected lock times.
3.3.5. Lock Detect Indicator
A lock indication signal can be made available on some of the DIO pins, and is toggled high when the PLL reaches its
locking range. Please refer to Table 19 and Table 20 to map this interrupt to the desired pins.
Rev 2 - Nov 2009
Page 18
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