SX1278

Both share the same die architecture, register map and QFN-28 package. The SX1276 tunes 137 to 1020 MHz, covering both the lower UHF and the 868/915 MHz bands, while the SX1278 covers only 137 to 525 MHz and is optimised for 433 MHz designs. The RF matching networks differ, so a PCB designed for one is not automatically optimal for the other - and because registers are identical, software cannot reliably tell them apart.

Use the PA_BOOST pin, set RegPaConfig for PA_BOOST output, and write RegPaDac (0x4D) to 0x87 to enable the +20 dBm high-power option; OutputPower 1111 then yields +20 dBm. Respect the datasheet limits: 1 percent duty cycle at +20 dBm and maximum antenna VSWR of 3:1. Expect roughly 120 mA of supply current, so your regulator and matching network must handle it.

Trade range against airtime and current. SF12 with 125 kHz bandwidth gives the longest range and worst data rate; SF7 with 250 kHz is the fastest useful LoRa setting. Narrower bandwidths improve sensitivity but demand a better crystal (use a 32 MHz crystal within 10 ppm, or a TCXO) and are more sensitive to frequency drift over temperature. For most 433 MHz telemetry links, SF9-SF10 at 125 kHz is a sensible starting point.

The chip is band-agile, so compliance depends on how you use it. In Europe the 433.05-434.79 MHz SRD band has duty-cycle and power limits (typically 10 mW ERP with 10 percent duty cycle), and in China sub-GHz low-power rules apply to the 433/470 MHz ranges. Verify your regional SRD regulation, antenna gain and duty-cycle budget during certification planning rather than after layout.

Software alone cannot fully prove the band variant, because SX1276/77/78/79 share register defaults including RegVersion 0x12 and RegFrf 0x6C8000. Combine checks: confirm RegVersion reads 0x12 (a non-0x12 value indicates a clone), measure conducted output power and receiver sensitivity across 430-440 MHz against a calibrated signal generator, inspect laser marking, package dimensions and lead finish, and demand lot traceability or X-ray inspection from the supplier.

Yes, and it is often wiser. Certified third-party modules based on SX127x silicon come with a pre-tuned matching network, antenna and test data, which removes RF layout risk and shortens certification. Confirm which exact Semtech part the module vendor references, request conducted RF test reports, and check that the SPI, DIO and power pin mapping matches your firmware.

Semtech lists SX1278IMLTRT in tape and reel with a 3,000-piece MOQ; we also supply 100 pcs loose for prototyping. Authorised channel lead time is normally 8-16 weeks. Our Shenzhen stock typically ships in 1-2 business days for up to 10,000 pcs, and finished 433 MHz LoRa modules are available on the same order.