Description

The HT1200M is a single-chip, CMOS modem for use in Highway Addressable Remote Transducer (HART) field instruments and masters. The modem and a few external passive components provide all of the functions needed to satisfy HART physical layer requirements including modulation, demodulation, receive filtering, carrier detect and transmit-signal shaping. The HT1200M is pin-compatible with the SYM20C15. See the Pin Description and Functional Description sections for details on pin compatibility with the SYM20C15.

The HT1200M uses Phase Continuous Frequency Shift Keying (FSK) at 1200 bits per second. To conserve power the receive circuits are disabled during transmit operations and vice versa. This provides the half-duplex operation used in HART communications.

Features

Can be used in designs presently using the SYM20C15 or equivalent type chip

Single-chip, half-duplex 1200 bits per second FSK modem

Bell 202 shift frequencies of 1200 Hz and 2200 Hz

3.3V-5.0V power supply

Transmit-signal wave shaping

Receive band-pass filter

Low power: optimal for intrinsically safe applications CMOS compatible

Internal oscillator requires 460.8kHz crystal or ceramic resonator

Meets HART physical layer requirements

Industrial temperature range of -40 °C to +85 °C

Available in a 28-pin PLCC and 32-pin LQFP packages

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