RFM95 Datasheet, PDF (76/121 Pages) List of Unclassifed Manufacturers – Low Power Long Range Transceiver Module

RFM95/96/97/98(W)
5. RFM95/96/97/98(W) Analog & RF Frontend Electronics
5.1. Power Supply Strategy
The RFM95/96/97/98(W) employs an internal voltage regulation scheme which provides stable operating voltage, and
hence device characteristics, over the full industrial temperature and operating voltage range of operation. This includes
up to
+17 dBm of RF output power which is maintained from 1.8 V to 3.7 V and +20 dBm from 2.4 V to 3.7 V.
The RFM95/96/97/98(W) can be powered from any low-noise voltage source via pins VBAT_ANA, VBAT_RF and
VBAT_DIG. Decoupling capacitors should be connected, as suggested in the reference design of the applications section
of this document, on VR_PA, VR_DIG and VR_ANA pins to ensure correct operation of the built-in voltage regulators.
5.2. Low Battery Detector
A low battery detector is also included allowing the generation of an interrupt signal in response to the supply voltage
dropping below a programmable threshold that is adjustable through the register RegLowBat. The interrupt signal can be
mapped to any of the DIO pins by programming RegDioMapping.
5.3. Frequency Synthesis
5.3.1. Crystal Oscillator
The crystal oscillator is the main timing reference of the RFM95/96/97/98(W). It is used as the reference for the PLL’s
frequency synthesis and as the clock signal for all digital processing.
The crystal oscillator startup time, TS_OSC, depends on the electrical characteristics of the crystal reference used, for
more information on the electrical specification of the crystal see Section 2.3. The crystal connects to the Pierce oscillator
on pins XTA and XTB. The RFM95/96/97/98(W) optimizes the startup time and automatically triggers the PLL when the
oscillator signal is stable.
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