Texas Instruments DAC8742HPBS

Overview

DAC8742HPBS from Texas Instruments is a dual-protocol industrial modem IC supporting HART® (1200/2200 Hz FSK) and FOUNDATION Fieldbus™/PROFIBUS PA (31.25 kbit/s Manchester) physical layer communication, integrated with UART and SPI digital interfaces, 1.5-V internal voltage reference, and programmable clocking (internal oscillator, crystal, or CMOS input). It operates across –55°C to 125°C and targets field transmitter and I/O module signal conditioning.

For engineers reviewing the DAC8742HPBS datasheet, DAC8742HPBS pinout, DAC8742HPBS application, or DAC8742HPBS equivalent, this device serves as a low-power, single-chip solution for bidirectional process automation communications requiring protocol flexibility, minimal external filtering, and robust carrier detection in harsh environments.

Technical Context

The DAC8742HPBS implements a half-duplex HART modulator using a 32-entry signed-sinusoid lookup table driven by a counter and DAC, generating continuous-phase 1200 Hz (mark) and 2200 Hz (space) outputs with <±1% frequency error over –40°C to 125°C. Its FOUNDATION Fieldbus mode integrates Manchester encoder/decoder logic, jabber inhibition, and 31.25 kbit/s transmit jitter tolerance of ±0.8 µs.

It features dual-domain power architecture (AVDD for analog, IOVDD for digital), configurable clock sources (XEN/CLK_CFG0/CLK_CFG1), and a shared MOD_IN/MOD_INF analog front-end supporting both internal band-pass filter (BPF_EN) and external filter paths - with distinct load capacitance requirements per protocol (5–22 nF for HART, 0–100 pF for FF/PA).

Key Specifications

Pinout & Package

Package: TQFP-32 (5 mm × 5 mm), Pb-free, RoHS-compliant, with exposed thermal pad (GND-connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with DAC8742HPBS, DAC8741HPBS removes SPI capability while retaining identical analog performance and temperature range, whereas AD5700-1ACPZ-RL7 trades dual-protocol support for lower BOM count in HART-only systems - making DAC8742HPBS the sole option for true multi-standard field device convergence.

Availability

DAC8742HPBS is available at Aetrix Electronics and suitable for industrial process transmitters, DCS I/O modules, and FOUNDATION Fieldbus segment devices requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for safety-critical deployments.

Supply support for DAC8742HPBS 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 company specializing in analog and embedded processing technologies, with leadership in industrial, automotive, and power management ICs.

The DAC8742HPBS belongs to TI's industrial communications portfolio, designed specifically to consolidate HART, FOUNDATION Fieldbus, and PROFIBUS PA physical layers into one robust, low-power IC for next-generation smart field instruments.

FAQ

What communication protocols does the DAC8742HPBS support?

The DAC8742HPBS supports HART (1200/2200 Hz FSK), FOUNDATION Fieldbus H1, and PROFIBUS PA physical layers - all implemented in a single IC. It does not support other protocols like Modbus RTU or CAN. The DAC8742HPBS achieves this through dedicated analog modulator/demodulator circuitry and integrated Manchester encoder/decoder logic, enabling seamless switching between modes via register configuration and IF_SEL pin control.

Does the DAC8742HPBS require external components for HART band-pass filtering?

The DAC8742HPBS includes an internal band-pass filter enabled by the BPF_EN pin; when activated, it requires only a single external capacitor (680 pF on MOD_INF for HART mode) to complete the filter. No external inductors or op-amps are needed. This reduces bill-of-materials cost and PCB area versus discrete filter solutions - a key advantage confirmed in the DAC8742HPBS datasheet Figure 3 and Pin Functions table.

What is the function of the IF_SEL pin on the DAC8742HPBS?

The IF_SEL pin on the DAC8742HPBS selects between UART and SPI digital interfaces: logic high configures SPI mode (enabling FIFO access, SDO daisy-chaining, and interrupt-driven transfers), while logic low selects UART mode (bypassing FIFO and aligning directly with HART BAUD rate). This pin must be driven externally - it has an internal pull-down but should never be left floating, per the DAC8742HPBS Pin Functions table.

Can the DAC8742HPBS operate with an external 2.5-V reference?

Yes, the DAC8742HPBS supports external reference input: when REF_EN is low, the REF pin becomes a 2.5-V ±62.5 mV (2.375–2.625 V) analog input. This allows use of higher-accuracy or temperature-stable external references where the internal 1.5-V reference does not meet system requirements. The DAC8742HPBS datasheet specifies 4.5 µA input current for external reference operation across all functional blocks.

What is the maximum SPI clock frequency supported by the DAC8742HPBS?

The DAC8742HPBS supports SPI clock frequencies up to 12.5 MHz, as specified in the Pin Functions table under UART_RTS / SCLK description. This allows high-speed register access and FIFO loading, reducing MCU overhead during burst data transfers. Timing parameters (e.g., tc = 80 ns minimum cycle time) confirm compatibility with standard 12.5-MHz SPI controllers without additional wait states.