LLCC68 datasheet(22/111 Pages) SEMTECH

22 / 111 page

LLCC68

Data Sheet

Rev. 1.1

DS.LLCC68.W.APP

Dec 2024

22 of 111

Semtech

LLCC68

www.semtech.com

4. Circuit Description

Figure 4-1: LLCC68 Block Diagram

The LLCC68 half-duplex RF transceiver operates in the sub-GHz frequency bands which support constant envelope modulation schemes such

as LoRa and FSK constant envelope modulation schemes.

4.1 Clock References

4.1.1 RC Frequency References

Two RC oscillators are available: 64kHz and 13MHz RC oscillators. The 64kHz RC oscillator (RC64k) is optionally used by the circuit in SLEEP

mode to wake-up the transceiver when performing periodic or duty cycled operations. Several commands make use of this 64kHz RC

oscillator (called RTC across this document) to generate time-based events. The 13MHz RC oscillator (RC13M) is enabled for all SPI

communications to permit configuration of the device without the need to start the crystal oscillator. Both RC oscillators are supplied

directly from the battery.

4.1.2 High-Precision Frequency Reference

In the LLCC68, the high-precision frequency reference can come either from an on-chip crystal oscillator (OSC) using an external crystal

resonator or from an external TCXO (Temperature Compensated Crystal Oscillator), supplied by an internal regulator.

The LLCC68 comes in a small form factor 4 x 4 mm QFN package and is able to transmit up to +22dBm. When in transmit mode the circuit

may heat up depending on the output power and current consumption. Careful PCB design using thermal isolation techniques must be

applied between the circuit and the crystal resonator to avoid transferring the heat to the external crystal resonator.

LLCC68 Datasheet(PDF) 22 Page - Semtech Corporation