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RF65
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ADVANCED COMMUNICATIONS & SENSING
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4. Operating Modes
4.1. Basic Modes
The circuit can be set in 4 different basic modes which are described in Table 12.
By default, when switching from a mode to another one, the sub-blocks are woken up according to a pre-defined and
optimized sequence. Alternatively, these operating modes can be selected directly by disabling the automatic sequencer
(
SequencerOff
in
RegOpMode = 1
).
Table 12 Basic Receiver Modes
ListenOn
in
RegOpMode
Mode
in
RegOpMode
Selected mode
Enabled blocks
0
0 0 0
Sleep Mode
None
0
0 0 1
Stand-by Mode
Top regulator and crystal oscillator
0
0 1 0
FS Mode
Frequency synthesizer
0
1 0 0
Receive Mode
Frequency synthesizer and receiver
1
x
Listen Mode
See Listen Mode, section 4.3
4.2. Automatic Sequencer and Wake-Up Times
By default, when switching from one operating mode to another, the circuit takes care of the sequence of events in such a
way that the transition timing is optimized. For example, when switching from Sleep mode to Receive mode, the RF65
goes first to Standby mode (XO started), then to frequency synthesizer mode, and finally, when the PLL has locked, to
Receive mode.
The crystal oscillator wake-up time, TS_OSC, is directly related to the time for the crystal oscillator to reach its steady
state. It depends notably on the crystal characteristics.
The frequency synthesizer wake-up time, TS_FS, is directly related to the time needed by the PLL to reach its steady
state. The signal PLL_LOCK, provided on an external pin, gives an indication of the lock status. It goes high when the
PLL reaches its locking range.
Three specific cases can be highlighted:
Receiver Wake Up time from Sleep mode
= TS_FS + TS_RE
Receiver Wake Up time from Sleep mode, AGC enabled
= TS_FS + TS_RE_AGC
Receiver Wake Up time from Sleep mode, AGC and AFC enabled
=
TS_FS + TS_RE_AGC&AFC
These timings are detailed in section 4.2.1.
In applications where the target average power consumption, or the target startup time, do not require setting the RF65 in
the lowest power modes (Sleep or Standby), the respective timings
TS_OSC
and
TS_FS
in the former equations can be
omitted.
4.2.1. Receiver Startup Time
It is highly recommended to use the built-in sequencer of the RF65, to optimize the delays when setting the chip in
receive mode. It guarantees the shortest startup times, hence the lowest possible energy usage, for battery operated
systems.
The startup times of the receiver can be calculated from the following: