Semtech SX1240/SX1242 RF platform

Semtech has launched a ‘power-and-go’ radio frequency platform that replaces infrared and RF discrete designs with an integrated, low-power radio solution for one-way remote keyless entry and remote control products in consumer, home/building automation; as well as active RFID applications.

The SX1240 and SX1242 ISM-band RF transmitters give designers an integrated solution, to enable true data-in/RF-out capability, with only an external crystal and antenna impedance matching network needed.

They simplify design, reduce system size and lower costs by integrating ‘power-and-go modes,’ which are preset for 434 and 868 MHz (SX1240) or 345 MHz (SX1242), eliminating the need for a microcontroller.

They also can be used with a wide variety of low-cost antennas that do not require active antenna retuning.

The devices can be paired with the company’s low-power SX1239 RF receiver for a complete radio. All three devices feature high operating efficiency and low sleep-mode current consumption, that makes them suitable for small, coin-cell battery chemistries and energy-harvesting sensors.

The transmitter operates in the 418, 434 and 868 MHz, ISM bands and works with FSK and OOK modulation formats up to 100 Kbps. For design flexibility, it offers two application modes. In ‘power-and-go’ mode, it can be preconfigured as either a 434 MHz OOK transmitter or an 868 MHz FSK transmitter, without the need for an MCU.

The 1240 extends battery life with an ultra-low, 16.5 mA (typ) current consumption, which is configurable at +10 dBm output power or 9 mA (typ) current consumption at 0 dBm output power, combined with a 500 nA (typ) sleep-mode current.

The low current consumption makes it suitable for coin-cell batteries, which are current limited at 20 mA. Combined with 1239 RF receiver, it features a high link budget of 130 dBm, allowing use of a very small antenna to further reduce the total design footprint.