Note: The Si4420 and Si4421 products are not available for new designs. For new designs, please use the Si4455 Sub-GHz Transceiver instead.
The Si4420/21 RF transmitters have a completely integrated PLL for easy RF design, and their rapid settling time enables fast frequency-hopping, bypassing multipath fading and interference to achieve very robust wireless links. The PLL’s high resolution allows the use of multiple channels in any of the bands. Highly stable and accurate FSK modulation is accomplished by closed-loop modulation with bit rates up to 256 kbps. In addition to the FSK modulation features, the microcontroller clock, wake-up timer, low battery detector, output power level and antenna tuning capability are also programmable through the serial interface.
*315 MHz band not available with Si4421