TRF6901

SINGLECHIP RF TRANSCEIVER

SLWS110G − SEPTEMBER 2001 − REVISED JUNE 2004

2

POST OFFICE BOX 655303

description

The TRF6901 single-chip solution is an integrated circuit intended for use as a low cost FSK or OOK transceiver

to establish a frequency-programmable, half-duplex, bidirectional RF link. The multichannel transceiver is

intended for digital (FSK, OOK) modulated applications in the new 868-MHz European band and the North

American 915-MHz ISM band. The single-chip transceiver operates down to 1.8 V and is designed for low power

consumption. The synthesizer has a typical channel spacing of better than 200 kHz and uses a fully-integrated

VCO. Only the PLL loop filter is external to the device.

Two fully-programmable operation modes, Mode0 and Mode1, allow extremely fast switching between two

preprogrammed settings (for example, receive (RX)/transmit (TX); TX_frequency_0/TX_frequency_1;

RX_frequency_0/RX_frequency_1;

…) without reprogramming the device.

ISM band standards

Europe has assigned an unlicensed frequency band of 868 MHz to 870 MHz. This band is specifically defined

for short range devices with duty cycles from 0.1% to 100% in several subbands. The existing 433-MHz band

for short-range devices in Europe has the great disadvantage of high usage. The new European frequency

band, due to the duty cycle assignment, allows a reliable RF link and makes many new applications possible.

The North American unlicensed ISM band covers 902 MHz to 928 MHz (center frequency of 915 MHz) and is

suitable for short range RF links.

transmitter

The transmitter consists of an integrated VCO and tank circuit, a complete integer-N synthesizer, and a power

amplifier. The divider, prescaler, and reference oscillator require only the addition of an external crystal and a

loop filter to provide a complete PLL with a typical frequency resolution of better than 200 kHz.

Since the typical RF output power is approximately 9 dBm, no additional external RF power amplifier is

necessary in most applications.

receiver

The integrated receiver is intended to be used as a single-conversion FSK/OOK receiver. It consists of a low

noise amplifier, mixer, limiter, FM/FSK demodulator with an external LC tank circuit or ceramic resonator, a LPF

amplifier, and a data slicer. The received strength signal indicator (RSSI) can be used for fast carrier sense

detection or as an on/off keying, or amplitude shift keying, (OOK/ASK) demodulator.

baseband interface

The TRF6901 can easily be interfaced to a baseband processor such as the Texas Instruments MSP430

ultralow-power microcontroller (see Figure 1). The TRF6901 serial control registers are programmed by the

MSP430 and the MSP430 performs baseband operations in the software.