LLCC68 datasheet(57/111 Pages) SEMTECH

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LLCC68

Data Sheet

Rev. 1.1

DS.LLCC68.W.APP

Dec 2024

57 of 111

Semtech

LLCC68

www.semtech.com

9.4 Standby (STDBY) Mode

In standby mode the host should configure the chip before going to RX or TX modes. By default in this state, the system is clocked by the

13MHz RC oscillator to reduce power consumption (in all other modes except SLEEP the XTAL is turned ON). However if the application is

time critical, the XOSC block can be turned or left ON.

XOSC or RC13M selection in standby mode is determined by mode parameter in the command SetStandby(...).

The mode where only RC13M is used is called STDBY_RC and the one with XOSC ON is called STDBY_XOSC.

If DC-DC is to be used, the selection should be made while the circuit is in STDBY_RC mode by using the SetRegulatorMode(...)

command, then the DC-DC automatically switches ON when entering STDBY_XOSC mode. The DC-DC is clocked by the RC13M. The LDO

remains active with a target voltage 50mV lower than the DC-DC one.

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 goes low as soon as the RX is enabled and ready to receive data.

The LLCC68 can operate with two levels of sensitivity:

• In Rx power saving gain, the radio consumes less power at a small cost in sensitivity

• In Rx Boosted gain, the radio consumes 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, or to continue using Rx Boosted gain when using the SetRxDutyCycle method, the following steps are mandatory:

• Set register 0x029F to 0x01

• Set register 0x02A0 to 0x08

• Set register 0x02A1 to 0xAC

Note: The above register addresses are not detailed in Table 12-1: List of Registers.

Table 9-3: Rx Gain Configuration

Rx Gain

Value

Rx Gain

0x08AC

Rx power saving gain: 0x94 (default)

Rx Boosted gain: 0x96

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