SX1240, Rev 1, Oct 2010

©2010 Semtech Corp.

SX1240

www.semtech.com

Page 9

Integrated Transmitter IC

ADVANCED COMMUNICATIONS & SENSING

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

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.

CTRL (Pin 6)

Configuration

‘High’

OOK 433.92 MHz, 10 dBm

‘Low’

FSK 868.3 MHz, Fdev = 20 kHz, 10 dBm