The TRF4400 single-chip solution is an integrated circuit intended for use as a low cost FSK transmitter to establish a frequency-agile RF link. The device is available in a 24-lead TSSOP package and is designed to provide a fully-functional multichannel transmitter. The chip is intended for linear (FM) or digital (FSK) modulated applications in the 433-MHz ISM band. The single-chip transmitter operates down to 2.2 V and is expressly designed for low power consumption. The synthesizer has a typical channel spacing of approximately 230 Hz to allow narrow-band as well as wide-band applications. Due to the narrow channel spacing of the direct digital synthesizer (DDS), the DDS can be used to adjust the TX frequency and allows the use of inexpensive reference crystals.