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SX1240 Datasheet PDF : 20 Pages
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ADVANCED COMMUNICATIONS & SENSING
SX1240
Integrated Transmitter IC
DATASHEET
3.1. Application Mode: Power & Go
3.1.1. ‘Power & Go’ Mode: Configuration
The default Power & Go application mode sees the SX1240 configured as detailed in the following table. By changing the
logical state of the control pin (6) at power-up, one of a pair of default configuration modes can be selected. The Power &
Go application mode hence permits microcontroller-less operation. By simply powering the transmitter application circuit,
the SX1240 is pre-configured as either a 434 MHz OOK transmitter or an 868 MHz FSK transmitter. For appropriate
matching circuits please see Section 5.
Table 7 Configuration and Band Selection in Power & Go Application Mode
CTRL (Pin 6)
‘High’
‘Low’
Configuration
OOK 433.92 MHz, 10 dBm
FSK 868.3 MHz, Fdev = 20 kHz, 10 dBm
3.1.2. Transmitter Operation in ‘Power & Go’ Mode
The timing of a typical transmit operation in Power & Go mode is shown in Figure 4. Here we see that a rising edge on the
DATA pin activates the transmitter start-up process. DATA must then be held high for the start-up time (TS_TR) of the
SX1240. During this time the SX1240 undergoes an optimized, self-calibrating, trajectory from sleep mode to transmit
mode. Once this time has elapsed, the SX1240 is ready to transmit. Any logical signal subsequently applied to the DATA
pin is then transmitted.
Figure 4. ‘Power & Go’ Mode: Transmitter Timing Operation
The transition back to sleep mode is managed automatically. In 868 MHz FSK modulation mode, after 2 ms of inactivity on
the DATA line, the SX1240 returns to sleep mode. If in 434 MHz, OOK modulation mode, the SX1240 waits for 20 ms of
inactivity before returning to sleep mode.
SX1240, Rev 1, Oct 2010
©2010 Semtech Corp.
Page 9
www.semtech.com
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