Low Power HART Modem with Precision Internal Oscillator

The AD5700/AD5700-1 are single-chip solutions, designed and specified to operate as a HART® FSK half-duplex modem, complying with the HART physical layer requirements. The AD5700/AD5700-1 integrate all of the necessary filtering, signal detection, modulating, demodulating and signal generation functions, thus requiring few external components. The 0.5% precision internal oscillator on the AD5700-1 greatly reduces the board space requirements, making it ideal for line-powered applications in both master and slave configurations. The maximum supply current consumption is 115µA, making theAD5700/AD5700-1 an optimal choice for low power loop-powered applications. Transmit waveforms are phase continuous 1200 Hz and 2200 Hz sinusoids. The AD5700/AD5700-1 contain accurate carrier detect circuitry and use a standard UART interface.

Applications

* Field transmitters

* HART multiplexers

* PLC and DCS analog I/O modules

* HART network connectivity

* HART-compliant fully integrated FSK modem

* 1200 Hz and 2200 Hz sinusoidal shift frequencies

* 115 µA maximum supply current in receive mode

* Suitable for intrinsically safe applications

* Integrated receive band-pass filter

* Minimal external components required

* Clocking optimized for various system configurations

* Ultralow power crystal oscillator (60 µA maximum)

* External CMOS clock source

* Precision internal oscillator

* Buffered HART output—extra drive capability

* 8 kV HBM ESD rating

* 1.71 V to 5.5 V power supply

* 1.71 V to 5.5 V interface

* −40°C to +125°C operation

* 4 mm × 4 mm LFCSP package

* HART physical layer compliant

* UART interface