A5191HRTLG-XTD
A5191HRTLG-XTD - HART Modem 1.2kbps FSK CMOS 32-LQFP | onsemi
The onsemi A5191HRTLG-XTD is a single-chip, CMOS modem IC designed for Highway Addressable Remote Transducer (HART) field instruments and master devices, operating on a 3V to 5.5V supply with a 1.2 kbps half-duplex FSK data rate using Bell 202 shift frequencies of 1200 Hz and 2200 Hz. Housed in a 32-pin LQFP (7x7 mm) GREEN package, the A5191HRT integrates modulation, demodulation, receive band-pass filtering, carrier detect, and transmit-signal shaping in one die, satisfying the complete HART physical layer requirements with only a few external passive components.
A HART modem is a specialized modem IC that enables bidirectional digital communication over the 4-20 mA current loop widely used in process automation. The A5191HRT sits at the physical layer of the HART protocol stack, overlaying a 1200 bps FSK signal on the analog 4-20 mA loop without disrupting the DC current measurement. Within the broader taxonomy, the A5191HRT is a wired transceiver/modems IC, part of the Interface ICs family in industrial process-control communication.
Key features include low power consumption with optimized sleep current, integrated transmit wave shaping for low total harmonic distortion, on-chip band-pass receive filter with carrier-detect output, and pin compatibility with the legacy SYM20C15, allowing direct drop-in upgrade of existing HART designs. The device supports both 3.3V and 5V microcontroller hosts and tolerates the industrial -40C to +85C operating range. The modem uses phase-continuous FSK at 1200 bps, with the receive path disabled during transmit operations (and vice versa) to conserve power.
Typical applications include smart HART transmitters (pressure, temperature, level, flow), HART valve positioners, HART-to-USB or HART-to-RS485 modem bridges, handheld HART configurators, and process-control I/O cards. Designers pair the A5191HRT with a microcontroller running the HART upper layers (command/data-link layer), a 4-20 mA DAC loop driver, and a small number of coupling transformers or capacitors on the loop side.
A practical design tip: place the receive filter capacitors and the loop-coupling network as close as possible to the A5191HRT analog pins (RIN, RXOUT, REF) to preserve the 4-20 mA loop's analog accuracy, and ensure the loop side meets HART physical-layer conformance spec #85 for noise immunity. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
USD $4,25
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