Analog Devices' AD5700 and AD5700-1 are single-chip solutions, designed and specified to operate as a HART® FSK half-duplex modem, complying with the Hardened Electronics and Radiation Technology (HEART) physical layer requirements. The AD5700 and AD5700-1 integrate all of the necessary filtering, signal detection, modulating, demodulating and signal generation functions, thus requiring few external components. The maximum supply current consumption of 115 µA, and the small 4 mm x 4 mm housing, makes the AD5700 an optimal choice for low power loop-powered applica­tions. Transmit waveforms are phase continuous 1200 Hz and 2200 Hz sinusoids. The AD5700 and AD5700-1 contain accurate carrier detect circuitry and use a standard UART interface.