LLCC68 datasheet(53/106 Pages) SEMTECH

53 / 106 page

LLCC68

Data Sheet

Rev. 1.0

DS.LLCC68.W.APP

July 2019

53 of 106

Semtech

www.semtech.com

9.5 Frequency Synthesis (FS) Mode

In FS mode, PLL and related regulators are switched ON. The BUSY goes low as soon as the PLL is locked or timed out.

For debugging purposes the chip may be requested to remain in this mode by using the SetFs() command.

Since the LLCC68 uses low IF architecture, the RX and TX frequencies are different. The RX frequency is equal to TX one

minus the intermediate frequency (IF). In FS or TX modes, the RF frequency is directly programmed by the user.

9.6 Receive (RX) Mode

In RX mode, the RF front-end, RX ADC and the selected modem (LoRa® or FSK) are turned ON. In RX mode the circuit can

operate in different sub-modes:

•

Continuous mode: the device remains in RX mode and waits for incoming packet reception until the host requests a

different mode,

•

Single mode: the device returns automatically to STDBY_RC mode after packet reception,

•

Single mode with timeout: the device returns automatically to STDBY_RC mode after packet reception or after the

selected timeout,

•Listen mode: the device alternate between Sleep and Rx mode until an IRQ is triggered.

In RX mode, BUSY will go low as soon as the RX is enabled and ready to receive data.

The LLCC68 can operate in Rx Boosted gain setup or in Rx power saving gain setup. In the Rx power saving gain, the radio

will consume less power at a small cost in sensitivity. In Rx Boosted gain, the radio will consume more power to improve

the sensitivity.

The Rx Gain register is not part of the retention memory when waking-up from a warm-start mode. To include this register

in the retention memory, the following steps are required:

•

Set register 0x029F to 0x01

•

Set register 0x02A0 to 0x08

•

Set register 0x02A1 to 0xAC

This procedure is mandatory when using the SetRxDutyCycle method, to keep on using the Rx Boosted gain.

Note:

In LoRa® mode, the user can also use the command SetLoRaSymbNumTimeout(...) to perform a quick and immediate

assessment of the presence (or not) of LoRa preamble symbols. If the user defined parameter SymbNum is different from

0, the modem will wait for a total of SymbNum LoRa® symbol to validate, or not, the correct detection of a LoRa® packet. If

the various states of the demodulator are not lock at this moment, the radio will generate the RxTimeout IRQ. Otherwise,

the radio will stay in Rx for the full duration of the packet. For more information, please see Section 13.4.9

"SetLoRaSymbNumTimeout" on page 89.

Table 9-3: Rx Gain Configuration

Rx Gain

Value

Rx Gain

0x08AC

Rx Power Saving gain: 0x94 (default)

Rx Boosted gain: 0x96

LLCC68 Datasheet(PDF) 53 Page - Semtech Corporation

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