RFM110W/RFM117W

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LDOs

POR

Bandgap

5. Functional Descriptions

VDD

GND

XTAL

XOSC

PFD/CP

Loop Filter

VCO

PA

RFO

Fractional-N

DIV

EEPROM

OOK Modulator

Ramp

Control

CLK

DATA

Interface and Digital Logic

5.1 Overview

Figure 11. RFM110W/RFM117W Functional Block Diagram

The RFM110W/RFM117W is an ultra low-cost, highly flexible, high performance, single-chip OOK transmitter for various 240 to

960

MHz wireless applications. The RFM110W covers the frequency range from 240 to 480 MHz while the CMT2117 covers the

transmitters, receivers and transceivers. The chip is optimized for the low system cost, low power consumption, battery

powered application with its highly integrated and low power design.

The functional block diagram of the RFM110W/RFM117W is shown in the figure above. The RFM110W/RFM117W is

based on direct synthesis of the RF frequency, and the frequency is generated by a low-noise fractional-N frequency

synthesizer. It uses a

1-pin crystal oscillator circuit with the required crystal load capacitance integrated on-chip to minimize the number of external

components. Every analog block is calibrated on each Power-on Reset (POR) to the highly accurate reference voltage

internally. The calibration can help the chip to finely work under different temperatures and supply voltages. The

RFM110W/RFM117W uses the DATA pin for the host MCU to send in the data. The input data will be modulated and sent

out by a highly efficient PA which output power can be configured from -10 to +13 dBm in 1 dB step size. RF Frequency, PA

output power and other product features can be programmed into the embedded EEPROM by the RFPDK and USB

Programmer. This saves the cost and simplifies the product development and manufacturing effort. Alternatively, in stock

products of

433.92/868.35 MHz are available for immediate demands with no need of EEPROM programming. The RFM110W/RFM117W

operates from 1.8 to 3.6 V so that it can finely work with most batteries to their useful power limits. Working under 3.3 V supply

voltage when transmitting signal at +10 dBm power, it only consumes 13.4 mA at 433.92 MHz and 15.5 mA at 868.35 MHz.

5.2 Modulation, Frequency and Symbol Rate

The RFM110W/RFM117W supports OOK modulation with the symbol rate up to 30 ksps. The RFM110W covers the frequency

range from 240 to 480 MHz, while the RFM117W covers the frequency range from 240 to 960 MHz, including the license free

ISM frequency band around 315 MHz, 433.92 MHz, 868.35 MHz and 915 MHz. The device contains a high spectrum purity

low power fractional-N frequency synthesizer with output frequency resolution better than 198 Hz when the frequency is lower

than

480 MHz, and the frequency resolution is 397 Hz when the frequency is higher than 480 MHz. See the table below for the