Data Sheet

LJ1269HC
Rev1.0 Page 34 Web: www.ljelect.com
4. Operating Modes
4.1. Basic Modes
The circuit can be set in 5 different basic modes which are described in Table 16.
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 16 Basic Transceiver Modes
ListenOn in
RegOpMode
Mode in
RegOpMode
Selected mode
Enabled blocks
0
000
Sleep Mode
None
0
001
Stand-by Mode
Top regulator and crystal oscillator
0
010
FS Mode
Frequency synthesizer
0
011
Transmit Mode
Frequency synthesizer and transmitter
0
100
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 Transmit mode, the LJ1269HC goes
first to Standby mode (XO started), then to frequency synthesizer mode, and finally, when the PLL has locked, to transmit mode.
Entering transmit mode is also made according to a predefined sequence starting with the wake-up of the PA regulator before
applying a ramp-up on the PA and generating the DCLK clock.
 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.
Four specific cases can be highlighted:
 Transmitter Wake Up time from Sleep mode = TS_OSC + TS_FS + TS_TR
 Receiver Wake Up time from Sleep mode = TS_OSC + TS_FS + TS_RE
 Receiver Wake Up time from Sleep mode, AGC enabled = TS_OSC + TS_FS + TS_RE_AGC
 Receiver Wake Up time from Sleep mode, AGC and AFC enable = TS_OSC + TS_FS + TS_RE_AGC&AFC
These timings are detailed in sections 4.2.1 and 4.2.3.
In applications where the target average power consumption, or the target startup time, do not require setting the LJ1269HC in
the lowest power modes (Sleep or Standby), the respective timings TS_OSC and TS_FS in the former equations can be
omitted.
Sub GHz FSK/OOK Transceiver Module DATASHEET