32Mhz Tcxo; Figure 6-1: Lr1121 Thermal Insulation On Pcb Top Layer; Figure 6-2: Tcxo Circuit Diagram - Semtech LR1121 User Manual

Refer to the LR1121 PCB reference design on www.semtech.com for an implementation example in PCB design.

6.2.3 32MHz TCXO

In environments with extreme temperature variation, it may be required to use a TCXO (Temperature Compensated Crystal
Oscillator) to achieve better frequency accuracy. When a TCXO is used:
•
The TCXO should be connected to pin XTA, through a 220Ω resistor and a10pF DC-cut capacitor. and associated
components.
•
Pin XTB should be left open.
•
The TCXO is supplied by the internal regulator on the VTCXO pin.
• The regulated VTCXO is programmable from 1.6 to 3.3V using command SetTcxoMode().
•
VBAT should always be 200mV higher than the programmed voltage to ensure proper operation.
•
The nominal current drain is 1.5mA, but the regulator can support up to 4mA of load.
•
Clipped-sine output TCXO are required, with the output amplitude not exceeding 1.2V peak-to-peak.
LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023

Figure 6-1: LR1121 Thermal Insulation on PCB Top Layer

Figure 6-2: TCXO Circuit Diagram

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