Texas Instruments DAC8742HPBSR

Overview

DAC8742HPBSR from Texas Instruments is a dual-protocol industrial fieldbus modem supporting HART® (1200/2200 Hz FSK) and FOUNDATION Fieldbus™/PROFIBUS PA (31.25 kbit/s Manchester) in a single TQFP-32 package. It integrates modulator, demodulator, band-pass filter, precision oscillator, 1.5-V reference, UART/SPI interface, and carrier detect logic - enabling direct connection to 4–20 mA loop transmitters and PLC I/O modules.

For engineers reviewing the DAC8742HPBSR datasheet, DAC8742HPBSR pinout, DAC8742HPBSR application, or DAC8742HPBSR equivalent, this device serves as a drop-in-ready physical-layer solution for safety-certified process automation systems requiring simultaneous HART configuration and FF/PA real-time control messaging with <180 µA quiescent current at –40°C to +85°C.

Technical Context

The DAC8742HPBSR implements a half-duplex HART physical layer using a 32-entry sine-wave lookup table DAC driven by an internal counter, generating phase-continuous 1200 Hz (mark) and 2200 Hz (space) FSK outputs with ≤1% frequency error over –40°C to +125°C. Its Manchester encoder/decoder supports MBP-compliant 31.25 kbit/s transmission with ±0.8 µs jitter tolerance and integrated jabber inhibition.

It features three clocking modes - internal 1.2288 MHz oscillator, external crystal (X1/X2), or CMOS clock input - selected via CLK_CFG0/CLK_CFG1, with CLK_O output configurable for system synchronization. The dual-domain power architecture separates AVDD (2.7–5.5 V) and IOVDD (1.71–5.5 V) rails to isolate analog integrity from digital switching noise.

Key Specifications

Pinout & Package

Package: 5 mm × 5 mm TQFP-32 (PBS), thermally enhanced with exposed thermal pad (GND-connected), JEDEC-standard footprint compatible with automated optical inspection and reflow.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar industrial fieldbus modem applications.

Compared with DAC8741HPBSR, DAC8742HPBSR adds SPI interface and FIFO for deterministic data throughput; compared with AD5700-1, it omits the 4–20 mA DAC but delivers full FOUNDATION Fieldbus H1 compliance - making DAC8742HPBSR the only choice for dual-protocol, loop-powered control nodes requiring both configuration and real-time control.

Availability

DAC8742HPBSR is available at Aetrix Electronics and suitable for industrial process control, PLC I/O modules, and field transmitter designs requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for DAC8742HPBSR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and industrial communications ICs - with decades of expertise in ruggedized fieldbus solutions.

The DAC8742HPBSR belongs to TI's industrial communications portfolio, designed specifically for seamless integration into safety-critical, loop-powered process automation systems compliant with HART, FOUNDATION Fieldbus, and PROFIBUS PA standards.

FAQ

What communication protocols does the DAC8742HPBSR support?

The DAC8742HPBSR supports two distinct industrial protocols: HART® (1200/2200 Hz FSK) and FOUNDATION Fieldbus™/PROFIBUS PA (31.25 kbit/s Manchester). It operates in half-duplex mode for both, with protocol selection handled internally based on register configuration and interface mode. The DAC8742HPBSR does not support Modbus, CAN, or Ethernet protocols - its design is strictly optimized for analog-loop fieldbus interoperability.

Can the DAC8742HPBSR operate with an external voltage reference?

Yes, the DAC8742HPBSR supports both internal and external reference configurations. When REF_EN is high, the internal 1.5-V reference is enabled and appears on the REF pin. When REF_EN is low, the REF pin becomes an input accepting a 2.5-V ±5% external reference. This dual-reference capability allows designers to trade off between board space savings (internal) and higher accuracy (external) depending on system requirements for the DAC8742HPBSR.

What is the purpose of the IF_SEL pin on the DAC8742HPBSR?

The IF_SEL pin determines the primary digital interface mode: logic-high configures the DAC8742HPBSR for SPI operation (with SDI/SDO/SCLK/CS), while logic-low selects UART mode (with UART_IN/UART_OUT/UART_RTS). This pin must be set at power-up and cannot be changed dynamically. Its state directly affects register mapping, interrupt behavior (CD vs IRQ), and FIFO usage - making IF_SEL a fundamental hardware configuration decision for the DAC8742HPBSR.

How does the DAC8742HPBSR manage power consumption in battery-powered applications?

The DAC8742HPBSR achieves ultra-low power operation through multiple mechanisms: power-down mode draws only 30–60 µA (–40°C to +85°C), internal oscillator consumes just 105–180 µA, and HART demodulator active current is 110–150 µA. Combined with carrier-detect wake-up via the CD/IRQ pin and programmable clock gating, the DAC8742HPBSR enables multi-year battery life in wireless gateways and portable configurators without compromising protocol compliance.

Is the DAC8742HPBSR pin-compatible with other devices in the DAC874xH family?

Yes, the DAC8742HPBSR shares identical TQFP-32 pinout and package dimensions with DAC8740HPBSR and DAC8741HPBSR. All variants use the same PCB footprint, thermal pad layout, and power supply connections. Functional differences - such as UART-only (DAC8741H) versus UART/SPI (DAC8742H) - are implemented internally and do not affect mechanical or electrical compatibility, allowing direct substitution in existing layouts where interface requirements align for the DAC8742HPBSR.