Microsemi has a new radio, Zl70550, that’s clearly better than the one we were looking at. the receive current is a little higher but the sensitivity is much better. The sleep current is only 10 nA vs 500nA. The maximum transmit output power is higher at lower power consumed (more efficient) only 5.3mA at 0 dBm. Compare with the nRF51822 that consumes 10.5 mA @ 0dBm. It has 40 dBm of RSSI range with 2dB of RSSI resolution.
With a typical current consumption below 2.75 mA in transmit (–10 dBm) and below 2.4 mA in receive (–95 dBm sensitivity), and a data rate of 200 kbit/s, the ZL70550 device enables bidirectional RF links over a distance of more than 100 meters (based on antenna gain and operating environment). A sensitivity of –106 dBm can be achieved by optionally increasing the receiver current consumption (to approximately 3.2 mA), enabling FEC, and using the lowest data rate.
The device includes the Z-Star protocol, which is a powerful and highly optimized MAC that performs complete packet transmissions with acknowledgments and automatic retransmissions on failed receptions. This built-in protocol eliminates the need for processor intervention in packet processing, allowing the processor to go to a power-save state or to perform other critical application processing. Additionally, the MAC supports other user modes of operation with selectable options like CRC, FEC, and auto length.