Melexis MLX72013 434MHz Low-Noise Transmitter

MLX72013 expands Melexis’ family of ISM Band RF transmitter ICs

November 23, 2011 - Tessenderlo, Belgium. The MLX72013 RF transmitter IC is a new member of the successful Melexis family of Wireless products. Optimized for use in an operating frequency range of 425 to 445 MHz, the MLX72013 is an ideal fit for applications using the world wide, 434-MHz industrial-scientific-medical (ISM) band standard.

A modified phase-locked loop (PLL) synthesizer in the MLX72013 enables the transmitter to operate the fully integrated voltage-controlled oscillator (VCO) reducing phase noise by 9 dB in comparison with the predecessor RF transmitter IC, TH72011. At the same time, the maximum transmit power of the MLX72013 is increased to 12 dBm compared with the TH72011. The improved power and noise features allow the MLX72013 to address the need for increased radiated antenna power as well as the more stringent modulation bandwidth regulations recently put in place in some countries.

Owing to its power select feature, the MLX72013’s transmit power is adjustable in four discrete steps ranging from -14 to +12 dBm. The pin configuration of the SOIC8 package is the same as for the TH72011. This allows designers a seamless move from the TH72011 transmitter IC to the MLX72013 without changing the printed circuit board (PCB).

Both modulation schemes, frequency-shift keying (FSK) and amplitude-shift keying (ASK), are supported. The FSK deviation can be set by two capacitors from narrow-band to wideband operation. A single-ended RF output is easy to match to many kinds of antennas, including PCB loop, wire whip or a helical antenna.

The MLX72013 is available in two temperature classes, for the automotive temperature range of -40 to 125 ˚C, as well as for the consumer-graded range of -10 to +70 ˚C. This allows the transmitter chip to be used in a variety of applications, including:

• Tire pressure monitoring systems (TPMS)
• Remote keyless entry (RKE) and passive keyless entry (PKE)
• Automatic meter reading (AMR)
• Alarm and security systems
• RF remote controls
• Garage door openers
• Home automation

In typical applications where a transmitter and receiver pair are needed, Melexis recommends the use of the MLX71121 RF receiver IC that has been optimized for non-automotive applications. In standard RKE or other automotive applications, the MLX71120 is the perfect companion to the MLX72013. In frequency agile applications, the MLX71122 multi-channel receiver could be used. An example of such might be when the combination of RKE or PKE with TPMS is required.

The following list summarizes the basic features and specifications of the MLX72013 RF transmitter IC:

• Drop-in replacement of TH72011 with reduced phase noise
• Frequency range of 425 MHz to 445 MHz
• Fully integrated PLL-stabilized VCO
• Single-ended RF output
• FSK modulation via crystal pulling
• Wideband FSK deviation possible
• ASK/OOK modulation via power amplifier modulation
• Wide power supply range of 1.95 to 5.5 V
• Very low standby current
• Low-voltage detector
• High over-all frequency accuracy
• Data rates from DC to 40 kbps
• Adjustable output power range from -14 to +12 dBm
• Adjustable current consumption from 3.8 to 16.8 mA