LLCC68 datasheet(103/111 Pages) SEMTECH

103 / 111 page

LLCC68

Data Sheet

Rev. 1.1

DS.LLCC68.W.APP

Dec 2024

103 of 111

Semtech

LLCC68

www.semtech.com

15.2 Better Resistance of the LLCC68 Tx to Antenna Mismatch

15.2.1 Description

The LLCC68 platform embeds a Power Amplifier (PA) clamping mechanism, backing-off the power when over-voltage conditions are

detected internally. This method is put in place to protect the internal devices and ensure long-term reliability of the chip. Considering a

high-power operation of the LLCC68 (supporting +22dBm on-chip), these “clamping” devices are overly protective, causing the chip to

back-down its output power when even a reasonable mismatch is detected at the PA output. The observation is typically 5 to 6dB less output

power than the expected.

Note: Using the described workaround improves chip functionality, but is not required to ensure long-term reliability, which is

guaranteed with or without workaround.

15.2.2 Workaround

During the chip initialization, the register TxClampConfig should be modified to optimize the PA clamping threshold. Bits 4-1 must be set to

“1111” (default value “0100”).

This register modification must be done after a Power On Reset, or a wake-up from cold Start.

The following pseudo-code can be used as a reference to implement the fix:

LLCC68 데이터시트(PDF) 103 Page - Semtech Corporation