Datasheet

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SX1272/73
WIRELESS, SENSING & TIMING DATASHEET
Rev. 2 - July 2014
©2014 Semtech Corporation
4.2.6. Startup Times
The startup time of the transmitter or the receiver is dependent upon which mode the transceiver was in at the beginning.
For a complete description,
Figure 18 below shows a complete startup process, from the lower power mode “Sleep”.
Figure 18. Startup Process
TS_OSC is the startup time of the crystal oscillator which depends on the electrical characteristics of the crystal. TS_FS is
the startup time of the PLL including systematic calibration of the VCO.
Typical values of TS_OSC and TS_FS are given in Section 2.5.2.
4.2.6.1. Transmitter Startup Time
The transmitter startup time, TS_TR, is calculated as follows in FSK mode:
,
where PaRamp is the ramp-up time programmed in RegPaRamp and Tbit is the bit time.
In OOK mode, this equation can be simplified to the following:
4.2.6.2. Receiver Startup Time
The receiver startup time, TS_RE, only depends upon the receiver bandwidth effective at the time of startup. When AFC is
enabled (AfcAutoOn=1) the AfcBw should be used instead of RxBw to extract the receiver startup time:
Sleep
mode
Transmit
Stdby
mode
FSTx
FSRx Receive
Timeline
0 TS_OSC TS_OSC
+TS_FS
TS_OSC
+TS_FS
+TS_TR
TS_OSC
+TS_FS
+TS_RE
Current
Drain
IDDSL
IDDST
IDDFS
IDDR (Rx) or IDDT (Tx)
TbitPaRampsTRTS ×+×+=
2
1
25.15_
μ
TbitsTRTS ×+=
2
1
5_
μ