LLCC68 datasheet(51/106 Pages) SEMTECH

51 / 106 page

LLCC68

Data Sheet

Rev. 1.0

DS.LLCC68.W.APP

July 2019

51 of 106

Semtech

www.semtech.com

9. Operational Modes

The LLCC68 features six operating modes. The analog front-end and digital blocks that are enabled in each operating mode

are explained in the following table.

9.1 Startup

At power-up or after a reset, the chip goes into STARTUP state, the control of the chip being done by the sleep state

machine operating at the battery voltage. The BUSY pin is set to high indicating that the chip is busy and cannot accept a

command. When the digital voltage and RC clock become available, the chip can boot up and the CPU takes control. At this

stage the BUSY line goes down and the device is ready to accept commands.

9.2 Calibration

The calibration procedure is automatically called in case of POR or via the calibration command. Parameters can be added

to the calibrate command to identify which section of calibration should be repeated. The following blocks can be

calibrated:

•

RC64k using the 32 MHz crystal oscillator as reference

•

RC13M using the 32 MHz crystal oscillator as reference

•

PLL to select the proper VCO frequency and division ratio for any RF frequency

•

RX ADC

•

Image (RX mode with defined tone)

Once the calibration is finished, the chip enters STDBY_RC mode.

9.2.1 Image Calibration for Specific Frequency Bands

Image calibration is done through the command CalibrateImage(...) for a given range of frequencies defined by the

parameters freq1 and freq2. Once performed, the calibration is valid for all frequencies between the two extremes used as

parameters. Typically, the user can select the parameters freq1 and freq2 to cover any specific ISM band.

Table 9-1: LLCC68 Operating Modes

Mode

Enabled Blocks

SLEEP

Optional registers, backup regulator, RC64k oscillator, data RAM

STDBY_RC

Top regulator (LDO), RC13M oscillator

STDBY_XOSC

Top regulator (DC-DC or LDO), XOSC

All of the above + Frequency synthesizer at Tx frequency

Frequency synthesizer and transmitter, Modem

Frequency synthesizer and receiver, Modem

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